The way I've always discovered good mechanics is to find one you think is
good, then offer him an inexpensive fix, maybe something you could do
yourself, and see how he performs.  Not just on price, but how quick a
turnaround, how clean the car is when returned, etc. etc.  Sounds like a lot
to do, but worth it if a big repair comes your way.  Good mechs are like
gold.  Also, you can sometimes use the truck-stop analogy--if the parking
lot has a lot of high end cars in it, porches, mercedes, and so forth, he
may be worth checking out.  Oh, one final thing...it never hurts to check
the BBB.  If people get burned for lots of cash, they tend to get irate and
will complain loud and hard.  I know I have in the years past.