Bought everything from no-name 1940's PA amp to vintage McIntosh's on eBay.
Common sense prevails when buying things on eBay. In addition to the feedback checking, etc., I try to get the feel for the seller from the description. If the seller is into audio and knows the equipment, showing some pride of ownership, there likely won't be any issue.
On the other hand, it'll be a gamble buying from a seller who claims to have found that McIntosh MC275 in a cave somewhere, and has no knowledge of how to test it.
I have seen that gamble can payoff big time, but I'm not a gambling man....