I didn't see the other post, seeker; who's the man/how did you know him? Have you talked to him at all since you gave him the guitar; it could take some time (or not). What was the last "excuse" he gave for not having sold it yet?

How much is the guitar worth? $75 to file a complaint seems a lot if you aren't sure you'll win (or if he splits or just gives you back the guitar and says he couldn't sell it, etc.).

I hope you've started documenting the whole thing before and can give him a call, tell him it's taken too long you want it back?