Depends - if they're true Blu-Ray rips at 40 gigs a pop (on average) then a 2TB drive he sells only has space for about 50 movies. Since he's claiming hundreds, that means he's using re-encoded ones down to fit on a DVD 9 or something. Squashing 40 GB to 9 GB incurs a quality loss (if it didn't, then no one would bother with Blu-Ray if they could fit a high def movie on DVD).
Oh, pirated material is often advertised on those sites. You're an idiot to pay since you can bet he just downloaded them the same way you could do it - for free. Plus I wouldn't use any form of identifiable method to contact him - email, phone or otherwise since if he gets busted (and selling pirated goods generally qualifies) he may roll over and hand over his customer list as a plea bargain. Commercial distribution of pirated goods is heavily frowned upon, even by those who file share.