So, if you're in the mood for a little hardware hunting, here are some guidelines I'd suggest so you don't get burned. This is high-end hardware hunting for seasoned pros. If you're no stranger to setting up a system manual-free and tinkering with its innards, then you are hereby cleared to hunt the landscape at will. Not at all, because I had a 56K modem gathering dust at home. The more peripherals you have to migrate into a new box, the better the value will be on a used system that winds up missing something like a sound card or a modem.
Detailed specs are very rare in an online auction.
Sometime you only get the CPU speed and the monitor's screen size. Make sure that any holes you find can be patched from your personal cache of cables, cords, and peripherals. Forget tech support That PC was either lovingly cared for, or customized into an annoying mess of drivers, add-ons and personal oddities best left unmentioned. But now it's yours. Make sure you know how to uninstall hardware and software and get a system back to basics without deleting the files and applications you plan to keep.