I personally have never had any experience with SMTN but the TSs listed there tend to be way overpriced. Have you checked out similar units on other resale sites such as here on TUG, E-bay, Red Week, My Resort Network, or Craigslist?
As for the broker or closing agent, who will pay the closing fees? You or the seller? If you agreed to pay them, then you should be able to choose which broker you want. If so, many other TUGgers can recommend reliable closing agents.