I haven't been at this for long Steve, but been burned a few times on the bay purchasing watches. Mostly because of my inexperience at the beginning of not knowing what to look for or recognizing aftermarket parts from original. And I know you are referring to entire watches, but I think what you are more commonly to come across if starting to get into collecting vintage seikos is poor quality replacement parts. I would suggest to trust the sellers here on the forum first, some of whom also sell on the bay like schillachi61 (Stefan) for parts. I've been able to acquire a few "good buys" on the bay but only after I became a little more experienced. Hope this helps, just my $0.02