I got 8 OEM (not pro, don't need the extra remote desktop options and that saved me some cash) cheap from newegg. No problems whatsoever except for metro.
Die, metro. Die.
Installed 8.1 the day it came out and haven't had any problems with that, either. Just recently went looking for a 8.1 iso since the 8.1 "upgrade" has to be done via the windows store, but found that M$ hadn't officially released a download outside of technet/msdn subscriptions up to that time and discovered a way around that. Installed from a "official" 8.1 install disk and smooth sailing after that. Even worked with my legit OEM key.