You might run into an occasional problem, but sellers I've dealt with are mostly good about returns or exchanges if there is a problem.
I did buy some AMD CPU chips one time from a guy. I needed 12 to upgrade some servers but only bought 4 at first. Worked great. Then I ordered 20. I received a flat envelope in my mailbox. I thought "Hmm, that's odd, it looks empty." Instead of being smart and opening it while taking a video, I just opened it and -- it was empty. I figured it was just a shipping mistake, called the guy, and he said he shipped them (actually he had a shipping person doing the packing so they might have been the thief) and I was trying to rip him off. He ended up giving me a discount on the 12 I needed but didn't refund the 20 I didn't get. It was the only place I could get them, unfortunately.
The way I look at it, I've gotten pretty good deals on everything at eBay, so if I get a little screwed once in a while, it all averages out to be okay.
No issues with the sellers or shipping AFAIK.
Mostly successful, but one of the big 4U disk arrays had some backplane issues and was a wash; the rest worked fine. The 4U was one of the more expensive pieces, though, and shipping was non-trivial. Not really a great choice but wasn't enough of a disaster to dissuade folks from considering it.
Never personally ordered anything more than $200 off it eBay directly. There is a reason you reach out to VARs, real estate agents, etc. when things start looking expensive.
That should be your limit for whatever you buy on eBay, the most fun I ever have on a night out is around $200.
Just bought a film camera, and a bunch of film. Between that and trying to get the photos developed, I probably wasted over $200, Camera never worked. Film didn't develop.
Such is life