This is a really good question that gets at the heart of the economics of armour production. Namely, what does the value of the armour represent - the armourer's labor that went into making it (in which case the cost is going to be generally reflected by the wages of the armourers) or the cost of the materials (in which case the cost of an armour will fare exceed the wages of the armourers)?

The answer to this is actually two-part. For normal armours, that is to say those that are simply made of steel and aren't exceptionally decorated, the value of an armour is primarily the labor that goes into it - nearly 90%. This is very unusual for most finished goods in the Middle Ages and early modern period, when, generally speaking, materials were expensive and labor was cheap, compared with the modern day (this is the dynamic that you see in trades like tailoring, where the cost of cloth is -far- more than the cost of the labor to make clothes*). In particular, much of the labor of producing a good quality armour was the polishing -according to Tobias Capwell, up to around 80% of the labor time was polishing. Keep in mind, though, that things like polishing and hammering could be partially mechanized with water power, which made them cheaper. What this meant, at the end of the day, was that -master- armourers producing good quality armour could earn a fair wage, and armourers in elite armouries like Greenwich would be fairly well compensated indeed - 17 pounds a year for the master armourer, 15 pounds for junior armourers and millmen, 12 pounds a year for locksmiths and 9 pounds a year for polishers, in addition to a clothing allowance enough to make at least 1 and possibly two suits of clothes a year. This compares well with skilled common soldiers, who were making 6 pence a day in 1492 and 8 pence in 1558, or a little under a pound a month (less than the locksmiths and maybe a little more than the polishers). This isn't extravagant wealth but it was a decent wage in a precarious time, and working for the king and earning a wage could be more reliable than the vagaries of the open market working for an independent armourer. On the other hand, independent armourers making fine armours for elite clients would not get a wage (unless they had a patron who was giving them a stipend or various gifts) but they would simply be paid the full cost of an armour.

But while this isn't bad, it, where did those hundreds of pounds go for those greenwich armours, if not to the armourer? For this, we need to look at the specific economics of truly elite armours. Because while the cost of a normal good quality armour is mostly labor, the cost of a luxury armour lies in the gold, and in the other decoration (such as etching, engraving, etc). For some exceptionally gilded harnesses, the cost of gilding would be a third of a fourth of the cost of armour, and another third or fourth would be the cost of etching (which would be paid to the artist etching the armour, not the armourer himself). For instance, in 1557 Andreas Brencker informed Archduke Ferdinand of Tyrol that an armour would could 400 florins, only two hundred of which was for the cost of steel and his workshop's own labor - the other 200 was evenly divided between the cost of gold for the gilding and the cost of etching. Moreover, a single luxury armour (which for several hundred pounds would not just be -one- armour but actually a garniture of several armours worth of interchangeable parts for different purposes) could take months to produce, so while the cost was great, so was the labor spent in producing it. So those hundreds of pounds could represent (mostly) tying up the labor of a dozen or so people for several months (not including workers outside of the armourer's workshop itself, like the etchers, goldsmiths etc).

To look at how an armourer who made luxury armours lived, we should turn to Filipo Negroli, one of the most famous armourers to ever live, and the only one named in Vasari's Lives of the Artists. Born to an armouring family in Milan in the first quarter of the 16th century, Filipo Negroli worked for at least 20 years, making outrageous and beautifully sculptures in steel and gold that could be worn by the princes of Emperors of Europe for parades, pageants and tournaments. His work changed what 'parade armour' went, and even as he was imitated he was never matched for opulence, beauty of form or fantastical creativity. They paid him, hundreds of florins for each luxurious armour. This money, and the inheritance of from his father (also a successful armourer) gave Fillipo a share in a house that he shared with his brothers and a country estate that he also shared with them. Compared with your average Milanese artisan, this was true prosperity, but it was a shadow of the wealth of the greatest merchants of the city. Indeed, some of his own relatives who traded in armour rather than making it were able to become the 16th century equivalent of millionaires.

I write a lot more about armourers, wealth and social class here.

*Of course, a lot of the cost of cloth is the labor to make it, which is often the underpaid labor of women who are spinning and carding etc. outside of the formal guild structure of the trades because they're too far up the supply chain but annnnnnyway.