I would never buy anything like parts without inspecting it/them. I buy stuff from Craig's List from time to time, but if I look at it and it seems sketchy, I walk out. I suppose if I was looking at a set of heads, and they were some less-than-common part, and I really wanted them, I'd make an offer contingent on inspection by a third party. If the seller balks at that, walk. JMO.