Bought my i7 quad core off Craigslist for $150...got scammed...had a trial version of Win 8 on it. Called up Microsoft...found out I could just buy a $15 Win 7 disk and return it back to factory settings.
Profit?
Yea, used that baby until I was able to build my own pc.
Edit:
The guy had the nerve to try and sell me his other PC after I told him how I fixed the one he sold me. Laptop was worth around $500, sold cheap because he said he "upgraded". Only thing he upgraded was the OS, he didn't know you could just revert it back to Win7 after using Win 8 trail.