Good friend doesn't mean fraud, at most it means bias.

Get a lawyer, oh wait, it's a small town, real estate agent, lawyer and hotel owner all know each other. So what?

Being good friend doesn't mean the agent will cheat for the hotel owner. It might mean agent would be biased. But who made the evaluation? Is the evaluation solid? If you want to sue, you cannot make jump in logic, you have to prove it.

Sounds like your friend bit off more than he could chew.