Ebay has almost every one of those Minolta lens up for auction, with every single lens condition described in great detail, and the feedback system on Ebay makes it a *very* reliable source (any sane EBay sellers would sooner lose some bucks than get negative feedback). Also, if there's a shop around, you can look at the lens and figure it out yourself. If there is a problem with the lens it would be apparent to anybody who knows what they are looking at, I can take my camera in my local shop and try out their lens before I buy it, testing the aperture blades, focus servos, and looking for any anomalies within the lens elements. I got my beercan (70-210) and 50mm prime at one, used, and I am in love with those 2 lens, done me well for about 4 years.

I really love Canon and I think they offer a great value and a great product as well but lets be real, considering the popularity of the system, legacy lens, and in-body stabilization, Sony offers a much better cost value right now.