I bought a Shelby Z last fall in a private sale that had 220 000 Kilometers on it. All the signs there were against it but it looked pretty decent and all the bills were there from its 11 year exsistance, including origial window sticker and bill of sale. Big Mistake! I have had to put tons of money into this thing, replacing lots of things but.. Before this car I had a very similar car that got destroyed (whole different story). I loved that car and it treated me well. It had a turbo as well and it was a joy to drive and own.
With the Shelby I can't say I hate it though. I love the car it self and the power she has. But it was in much rougher condition than I had ever imagined. Basically all I am saying is really check out what you are buying here. If you get the right one they can be a lot of fun. But to be honest they are prone to some problems because people bag the engines lots because of the general nature of the car, having a turbo and all. If you can find one in excellent shape, I would say go for it! You'll have tons of fun but if you even suspect a problem.. Run like the wind!