I have bought an item around 5500 from AuctionTime no problem but with an item of this nature.   I would maybe suggest using an independant:
          escrow agent n. a person or entity holding documents and funds in a transfer of real property, acting for both parties pursuant to instructions. Typically the agent is a person (commonly an attorney), escrow company or title company, depending on local practice.

I'm sure there will be a small fee involved and Auction Time might tell you that is what they are, but they have a vested interest.  Therefore, I would do a google search and find an escrow company and give them a call in the AM.    This is real common when buying/selling Aircraft. 

         Goodluck!  Badger might chime in on this he has been in a few rodeo's.... lol