Hey everyone - I'm trying to scratch an old-school itch for D&D modules this year.  My son is getting into playing with his friends, and I'm looking to get back into some of the old-school source material to run games for them.  Is there a suggested vendor who specializes in this stuff?

Thanks in advance!

The Auction and the Consignment Store are guaranteed to have a bunch of books from 2nd, 3rd, 3.5th, 4th, and 5th Editions (Pathfinder too, if that counts as old-school these days).  The Exhibit Hall vendors who actually specialize in used older material have slowly dwindled over the years, unfortunately, though there are usually a couple (Games Plus is probably going to have a booth, and they are a great store/vendor and will have some; might be someone else too)

Games Plus is your stop for older stuff (and Bob is a good dude). For new stuff hit our booth #2801 and we'll have ya covered. As pointed out older stuff has pretty much migrated to the auction and online as the prices have really skyrocketed in the past few years.

Amazing!  Much appreciated, everyone!

Goodman Games has converted/reprinted a number of older modules into 5e and DCC.