I'm a former mechanic, and usually astonished at what most shops get away with.
I've seen $1200 tune ups. (Six cylinder Ford Vallant, and the shop owner told my friend business was slow that week, and he needed money.)
To a Franchise owner at Aamco (San Rafael, ca) who told he the tranny was going into limp mode when he test drove it, and then brought me into the office to look at the cutaway model. (It was never even driven because he didn't have the key. Plus--when he realized I knew the lingo; he started kissing my ass. He knew he was caught. He was a new franchise owner, but that's no excuse.)
My point is there's some real business opportunities out there. An honest shop is gold. Its a very tough business though. I've even met some people who sware their "guy" is the best. They are usually the ones who are being taken the most.