It depends on a few different criteria. Which resort you buy at, if you buy direct from Disney, how many points you buy, etc. etc.
If you want Saratoga Springs, the initial buy in is 150 points until February 28. In March, the minimum contract goes up to 160 points. Right now you can buy SSR from Disney for $91/point if you give up the current use year's points. You can buy any of the sold out resorts direct from Disney as well, but I do not know what that cost is.
You can also buy from the resale company who sponsors this board. In general, a resale will cost less than buying direct, depending on the resort you are looking at. For example, BCV is a small resort, and popular because of it's proximatey to Epcot. Resale prices on small BCV contracts can actually be more than the same number of points direct from Disney.
You also need to look at the maintenance fees and their history at each resort. Currently, SSR and OKW have the lowest maintenance fees. If you go to
http://personalpages.tds.net/~rb/DIS/DVC/DVCDuesHistory.htm, there is a history of
DVC dues compiled by Robinb.
So you see, there really is no one definitive answer to your question.