My mother bought a Compaq from eBay a long time ago, and it was a terrible idea. I didn’t work right when we got it. I won’t trust PC components from eBay. I prefer to buy from Microcenter, because they’re actually an enthusiast’s place, and I can buy a 2-year warranty for parts, which is what I did for my mobo, AMD APU, and SSD.
All in all, cost me around $600. Gaming capable on low settings as well. I’ll be using it for years.
I have bought lots of computer gear on eBay and, knock on wood, I’ve never had a problem. I have used MicroCenter for years, mainly when I’m in hurry to get something fast.