I can also wholeheartedly recommend The Timeshare Store. We purchased one of our resales thru them and they did a great job. That being said.............
For the best purchase you do need to shop around all of the sites and find the best contract for you. Yes, the Timeshare Store's impeccible service may smooth the process a little more than some of the other brokers, but if someone has listed the perfect contract for you (right number of points, best use year, banked points, great price, etc.) with someone else you have to at least consider making an offer.
We used Lee Reid for our other resale purchase. His service wasn't as good as the Timeshare Store, but the process took about the same amount of time and we have been satisfied with both purchases.
So, looking around and doing your homework is the best way to buy a resale. Looks like you have got the homework part going, now they just have to find the perfect cpontract for them. Good luck.