This is before industrial production, so made items require hand labor, and are therefore expensive. So poor people would have noticeably less things than rich people, generally, but even rich people might not have as much stuff as you would today. This is obvious, but we have today such a huge consumer-society that it's easy to forget. One small example; this is a world where you could go to an inn and rent a pipe and buy a little tobacco to smoke in it, and if you stayed the night there would be an extra charge for a candle- and if you were not staying up to play a card game with someone, you might well think a candle was an extravagance ( which is where the saying "the game is not worth the candle" came from).

One very obvious distinction would be imported goods. Much before 1700, of course, much of the goods ( if not most) would be imported. But as the colonists began to make their own things, it would be rich people who could afford the imports more than poor. A farmer might get a fowler ( shotgun), locally made, for 4 pounds: George Washington might order a fine one from London that cost 8.

The same would apply to clothes. And here you would also be able to pick out the rich from the poor, because not only would the rich tend to have finer clothes, made from imported silk instead of homespun linsey-woolsey, but they would have more of them. Someone quite poor could be ragged, patched. This would be another signifier: Beau Brummel famously declined to have any of his clothes mended, because a tear or rip could have been a recent accident, but a mend or a patch was a sign of economy, possibly poverty.

Linda Baumgarten;  What Clothes Reveal: The Language of Clothing in Colonial and Federal America 

To expand on /u/Bodark43's point about clothes (because I can and not because I think that was a bad answer, for the record!):

Most of all types of fabric were being imported to the colonies, in large part because Great Britain wanted America dependent on British goods. In the earlier part of the American colonial period, printed cottons were much more expensive, but by the 1770s-1780s there were cheaper, one- or two-color prints with small, dense patterns that could be afforded by many as well as the more naturalistic, multicolored representations of flowers and vines that would be reserved for the wealthy. Slave and servant runaway advertisements give some very good information on what the poor were wearing.

Laurel Thatcher Ulrich's Age of Homespun is a very good look at the related tropes and realities of the era. In rural areas, where 90% of the people in the colonies lived, "homespun" was about more than just home production for home use, but involved a network of production. Many women spun flax (linen) or wool that could be taken to a (male or female) neighbor with a loom who wove as a side job, for instance. Or a girl might be hired for a few days specifically to spin the flax or wool that a farm had produced. Homespun fabric wasn't exactly the lowest rung on the ladder because it required a certain amount of money and property to create; that said, it was more desirable for use in sheets, tablecloths, etc. than for clothing.

There were also very fine craftsmen in the cities (Boston, Philadelphia, New York, etc.), and the Metropolitan Museum of Art can tell you about colonial American furniture and the levels of quality available.

I'm not going to argue entirely against what has been said, but I don't fully agree that the colonists had only a few low-grade items. Importation was HUGE and luxury goods made up a lot of it. Fashionable fabric was the largest import into the colonies during that time, for example. It made up over a third of the value of all imports.

When it comes to difference between expensive and cheap the simplest way to think of it would be quality. All goods are imported into the Colonies at this point. What is done trade-wise in the Colonies is done because it cannot be done else where. It is cheaper to import a good than make it here (sound familiar?). That's because there are large cities overseas that specialize in certain products and have large-scale unemployment problems, meaning they can get a lot of cheap labor and have the industry set up to make the goods. On the other hand, the colonists have low man power and don't have industrial sites set up yet. A black smith in the colonies will not specialize, but repair things or make items that need to be made locally (if you need a new key you don't want to send the lock to England). In England a blacksmith might just make nails and that's it. It makes nails from England much cheaper than local.

Because of this process, the quality goods also came from the same cheap sources. They were very good at what they did, so relying on imports was not a step down. Nor was it a step up. There weren't other options. Colonial Williamsburg recently had a conference on textiles in America and one of the big panels was about "Homespun" (made up of Linda Baumgarten, Karen Clancy, Mark Hutter, Janea Whitacre, etc). It's long been thought that there was a decent sized population that wove their own garments within small communities, literally spun in the home. The research done for the panel, focused around the Homespun Balls, found instead that homespun meant simply made in the Colonies and even includes things like silk woven in the Carolinas that was sent to Queen Charlotte, who had gowns made from it for her and her daughters. Because of the sheer labor that goes into making these textiles it'd be nearly impossible (even for a small community) to make enough to be worth while, and it'd be more expensive than imports. It seems homespun was more of a novelty than a useful thing. It was not available in local stores. The estimates from the beginning of the war made by the government found that working full power the Colonies could supply about 10-15% of the fabric needed for regular use. And most of the existing industry was on plantations for plantation use. It was said that only enough cotton was grown in the Colonies "to keep the elderly Negresses at work."

So, if both rich and poor are buying from the same sources, where's the difference? It's just quality and fashion. Just like today, certain colors are in for the season and out in a few months. You can buy your winter coat for less in March than in November. If you want the most fashionable clothing, but can't afford much, you buy lower quality fabric. It costs the same to have it made up into a gown or suit no matter the textile. Note that a plain gown in Virginia costs only 2 1/2 to 3 shillings in labor, taking only a day to make it only costs what the Mantua maker earns daily. Not expensive, but she wouldn't be poor on that daily wage either. Hand-work is expensive in modern day, but not then. It was the only option so it HAS to be affordable for all. The fabric is likely to be at least 2 shillings a yard for cheap, but decent textiles, needing 4 or more yards a gown, so our cheap gown has at least 8 shillings in fabric and 3 in the labor. It could be hundreds of shillings per yard, however, so the price is really in your hands. Meaning a poorer person might have only a few nice items or a great many cheap ones (which would be more practical since their job probably doesn't require nice things).

Etiquette books of the 18th century recommend not spending more than 30% of ones income on clothing and other fashionable goods. Estimates for modern day are usually 5-10%. We instead have cars, computers, tv, etc. to spend on. The thing you might be noticing here is that there isn't going to be a stark difference between the wealthy and the poor in all things. If someone owns a silver punchbowl we can tell that they are wealthy, just like someone driving a Tesla today. But can we tell if the person driving the Tesla spent $20 or $2000 on the jeans they are wearing? Probably less easy. And it was something noted in the Colonies as well as England. Many jokes were made about the gentleman greeting the maid before the lady when he passed them in the gardens. A Frenchman visiting the Colonies noted that it was hard to tell the ladies from the maids they were are dressed so finely.

So, what would be outrageously expensive? Precious metals and gemstones, obviously, in large quantities could be very costly (but also imitated by things like paste jewels). The latest fashionable printed cotton from India with five colors at 20 shillings a yard, rather than it's messier imitation with only one or two colors at only 5 shillings. A gown made from silk with silver woven into it is unmistakably expensive, though its sleeve might be made from 20 tiny pieces of scraps to use every last bit. A human hair wig rather than hair pieces or using horse hair. Or simply having a lot of something, like Lord Dunmores pounds of blue hair powder that were recorded when he died. Simply, if I own a pair of Ferragamo shoes I might have saved up for it, but if I own twenty that shows wealth. The Colonists were huge consumers on all levels, and because they had more work to be done than people, they were paid well for it. A tailor in England had a set minimum wage of about 1 1/2 shillings a day. In Williamsburg, VA there is an advertisement for new Journeymen tailors to be paid 5 shillings a day and that's not unusual for the Colonies. If you were able to work, you could find it (if not the parish church provided). In London it's estimated that half of the population was only working half of the time they could have. So, poor in the Colonies is very different than poor in London or Paris.

Oh, one final thing, when you see records of the wealthy buying direct from London rather than through local shops it's not so they can get better goods. Though it's always something of a brag to say it's the latest from London, the shops advertise that as well and the suit you had shipped over came just as fast as the same fabric and magazines showing that style. It's simply because their money is tied up in England. A wealthy land-owner sells his crops directly to a buyer in England rather than through a local buyer. He cannot remove more than 10% of that in cash. The rest goes on credit in England and a buyer purchases all of the things they need. Personal items, such as a made up suit or gown, are not taxed, but yards of fabric would be (could be resold). George Washington bought his suits from a tailor in London but always complained that the sleeves were too short despite sending measures. He had problems with furniture as well, the doors and drawers stuck due to the change in humidity. Sometimes locally made is the better choice, but he wouldn't have had the easy access to his income to buy it.