I'm with the previous posters, "all" the resales out there are a drop in the bucket when you look at how many of us there are. A lot of people sell their points b/c they want to buy into disney's latest vacaion club and want their 11 month window to be there bc they travel at peak times. We bought ours on the resale. Our sellers were starting a new business and needed fast cash. They had about 1/3 of their points from that use year and none borrowed. We'd called a couple of resale realtors and told what we were looking for - OKW (b/c the dues are cheapest there and we're really flexible about where we stay), with at least some points left on the current year, none borrowed from the next, and our range of desired points. We received a call about a week later that something had come in, and we made an offer, it was accepted immediately by the seller, and in about 4-5 weeks we found ourselves staying in an OKW studio for three nights to celebrate Mickey's Not So Scary. We've found that in an OKW studio (or standard BWV studio) we are actually paying less then if we stayed in a regular hotel (that was a little better then Days Inn) off property when parking is factored in. We love the early admission, we leave the parks around 1pm to rest/avoid crowds, and return later. We have annual Seasonal passes and it works great for us.
Now, on the other hand, my sister has a beach timeshare in South Florida, it is a nice 1 bedroom timeshare about a half hour from both our homes, and she has never really used it even though she bought a "great week", she would be unable to sell it for what she paid for it, and her dues are about what OKW is for 100 points or so. She has no flexibility with staying weekends only either. She (for some unknown reason) won't sell it and cut her losses. I guess she feels bad if she sells it, I don't know. It is an RCI or whatever. They traded once.
Maybe you don't see so many other timeshares out there for sale b/c 1.) there isn't much of a market for them, and 2.) because at most timeshares (like my sisters) there aren't more then 100 units. If you look out there I'm pretty confident you'd find quite a few Mariotts and Hiltons for sale too, just b/c of the sheer number of them that exist. I'd love to add on points at OKW in the future, when my finances allow, so I hope that they keep popping up.
Like others have said so well, timeshares are not right for everyone. THey weren't for me either until recently.
Good luck deciding.