There are a few things you should know about point rentals.
1) Treat the reservation as non-refundable - even non-movable. Plan on having the reservation you make be the trip you take. If you have to cancel, chances are you will not get your money back, and you may not be able to move your trip. If you are in a position where not getting your money back if you need to cancel is a BIG DEAL, book through CRO.
2) Its a private transaction between you and who you rent from. If you get there and there is no room - Disney is not involved at all in the transaction. Doesn't happen often, but it does once in a while. When you look for a member, look for someone with a history here - they are unlikely to risk that history on a scam.
3) Understand what you are getting - DVC rooms often book quickly, particularly the bargain rooms - if you are looking for a low point room this summer - its probably too late. In a studio there is a queen bed and a full pullout (Except at OKW where there are two queen beds). There isn't daily housekeeping. You often don't get into your room until AFTER 4pm. These are the things members - as well as renters - take in exchange for a good value (and most members don't mind no daily housekeeping, some like the pullout in the studio). No
Free dining. You will not be entitled to member discounts or perks.