Hi, Jim - - -
Even in our highly litigious society, your case is going exactly nowhere, unless . . .
Did the previewing mechanic in any way warrantee his inspection?
Unless he gave you a very specific, *written* statement of facts, there's no legal leg to stand on. A friendly attorney might be willing to draft a threatening letter for you, but he'd likely be handling it with great care and little expectation of positive result.
Now if the "we" with which you opened you letter *both* heard verbal assurances of perfection, you might possibly have something to go on, but I think that Small Claims Court would be the appropriate venue. In most jurisdictions, the SCC limit is now up to $5,000, so you could recover if the judge were to find in your favor. There is that tiny edge going that the mechanic is the "expert" and you are the "trusting novice" with every reason to take his word has gospel.
Again, though, the written word is the key here. I'm no attorney, but I have spent a lot of time in SCC over the years - partly relating to the fact that I was once in the car business.
Good Luck!
bob noble Reno, NV, USA