I've used Farmers in Marchmont (tyres, brakes), and the Marchmont Garage (Thirlestane Lane) (MOT, exhaust), and both were OK. No idea if they were "cheap", but they did OK work. Guy at Marchmont Garage did a free suspension check for me as well, when I though something felt funny. Farmers is now open 8-8 during the week, too, if you're in the library all day ;)
I didn't like the Citi Coachworks – cash in hand, no receipts type of stuff.