I'm late to this thread, but I just wanted to say that renting DVC points was a fantastic experience for me. It's not cheaper than staying offsite, but you can get a better-than-deluxe room for moderate rates.
Even though you're not going until May, it can't hurt to put out a request right now. If you don't get a reply, just wait a month and try again.
Also, the trust factor can be a little scary, especially since there really isn't a feedback system like on eBay. As a rule of thumb, though, if you rent from someone who is a long-time member on these boards, you almost certainly can't go wrong. Still, if money is so tight that your entire vacation would be destroyed by a deal gone wrong, this may not be the way to go.
Also consider the possibility of staying offsite for the first night if you arrive on a Saturday, it will save you tons of money.