We have used different people for ours. My first experience was through eBay of all things. Got to know the lady and still use her business. She pointed us to VRBO and FlipKey. We found Vacation Strategy though FlipKey and had great experience. From there, I found other places to meet renters. One site was a pay site (I think $18 a year). I found an owner that just got Platinum VIP status. He also purchased another 500,000 points on top of it. He got me a 1BR Dlx for $560 for 7 nights.
You just have to look and find out who you are comfortable with. I know what the person will do with the reservation as it gets closer. They are going to dump and re-register it for 50% of the points. For me it is no issue. The points were 166,000 for our week. I still get a great deal and the owner gets 83,000 points back to rent again.