Best place to buy a used performance car?

[laser7]

Aside from a dealership, what's the best place to buy a used performance car? I see many ads from dodgy-looking used car traders that don't fill me with confidence. Some prices look too cheap to be true. A quick Google search shows up a few bad experiences. Obviously no purchase is risk-free, hence I'm trying to reduce the risk.

[Atmospheric]

What sort of performance car? Depending on the type and age this differs.

AUC is a good start, but you pay more, but there is a certain amount of confidence with manufacturer warranties etc.