Hey Russ...I may have missed it in there somewhere, but...have you just told the guy that you have other buyers and he needs to get off the pot on this if he is going to close the deal?
Legally, (depending on your state) you probably don't even have a oral agreement since you didn't stipulate how long. If it was me, I would call the guy, tell him you need it done by XX/XX/XXXX or it goes to the next buyer, then follow that with a letter confirming that (registered/return receipt). Give him 5 to 10 days and after that....move on.
