I've been doing the DVC math lately, and I think it can work if we buy a small contract resale. We have two adults and three kids. Ideally, I'd like to buy 25 or 50 points and use them every 2-3 years. Buuuuuut, the math only works if we can all get in a studio... the cost in points for a 1BR (and that's not even cut-and-dry for 5 it seems) is double that of a studio. I know the Poly and Grand Flo definitely fit 5, Wilderness Lodge fits 5 depending on who you ask (I've seen at least one site saying 5, but the fifth brings their own bedding... not a problem for us), and the rest seem like a definite "no"? And what are the chances of actually booking at these resorts that fit 5? Anyone have some clarification?
In any of the studios, even the large ones like GF and Poly, 5 people will be a very tight fit. If you can only afford enough points to rent a studio, then I'm not sure DVC is the best option for you. I don't know what the minimum contract for a resale purchase is, but if you go through DVC, the minimum contract is 50 points.
And you need to understand banking your points. If you only go every two years, then you will have double the points available since you will be banking one use year into the next. However, if you don't use those banked points in the next use year, they go bye bye. For example, you purchased 50 points in Use Year 2015 (for simplicity, your use year ends December 31st). You don't go this Use Year and bank those points to Use Year 2016, so now you have 100 points to use in 2016. And once points are banked, you cannot unbank them. So, if you decide you want to take a weekend trip in 2015, you will have to borrow points from 2016 (but not the banked ones. Yes, I know it gets confusing).
And don't forget the annual dues, which will be based on the number of points you own. The annual dues for my 25 points at GF were about $160. Dues cover property taxes and what Disney calls an operating reserve, i.e., cost of operating the resort - maintenance, housekeeping, renovations, etc. And if there are planned renovations in the future, expect your dues to increase.