really, in the flesh they're pretty easy to tell apart. they're European pressed and have flat labels, no dip around the centre, paper label usually doesn't quite reach the edge of the raised area, etc. besides just the paper and print quality. online of course, have to be careful, but that goes without saying for expensive records, surely?
as for the profit - well the guy making them isn't selling them at 6 quid, he'll get about 3 quid from the shops and dealers.