This is an excellent question, and to be honest I have no definite answer. One could try looking through newspaper archives to find property advertisements, or through the records lefts by wills to see what people owned when they died, and what they passed on to their inheritors. I'm afraid I don't have the time to do that at the moment though, so you'll have to make do with some best guesses. If you're in London, the London Metropolitan Archives would be the place I'd suggest one start to look; the British Library's Newspaper Room also has an extensive collection of newspapers--naturally--but I don't recall coming across many advertisements of any kind; then again, when I was reading through years of trade journals, I wasn't looking for them. So who knows what you'd find.

What I can say, is that in property terms, £10 was probably not much at all. Maud Pember Reeves's classic Round About a Pound a Week was a look at East London working-class people who lived on a weekly income of about a pound. She did this research from 1909 to 1913, and found people barely scraping out a living. Many of them spent virtually their entire incomes on food, relied on support from friends, family, or various charitable organizations, and owned practically nothing other than their clothing and the very barest minimum of household items. I recall one story--perhaps not from her specifically, but illustrative--of a family pawning their lamp because they couldn't afford oil and preferred to have a few loaves of bread in the dark than a useless lamp. These are the sort of people that B. Seebohm Rowntree described in his 1901 study of York, Poverty: A Study of Town Life, as living in "extreme poverty" or "extreme distress." So, if these are families getting by on a pound a week, £10 of property certainly isn't nothing, but it's not a whole lot, either. The historiography tends to treat the 1884 Act as enfranchising the great bulk of the working population, and the prices I've noted here bear that out.

I'm not an expert, but I was taught that property in England was reckoned by its rental value rather than its sale value. This is partly because, in a post-feudal society, a lot of property changed hands only by inheritance. Land taxes were reckoned by a system called rates, where surveys were done and a 'rateable value' based on rents were set by rate commissioners. There are a few properties which were handed to a family by a mediaeval king, and have not been bought or sold since. No Title Deed exists for these properties and no resale value has ever been officially calculated, but rates could be collected based on the rental value of farms and dwellings within these properties.

This system was only abolished in the 1980's, and a few details based on established church tithing rights are only now undergoing a 10-year cooling-off period before final abolition.

This copy of the Representation of the People Act, 1884, with commentary seems to bear out this view, as I think it extends the franchise to men who pay £10 rent per year, or who receive it (at page 16).

I believe that 'property worth £10' meant property whose annual rent was £10, rather than property that could be bought for £10.