It would really depend on where you live, i know amazon do them but they're quite pricey. If you live in the UK then CEX is a good place to pick up DVDs and games.
I've compiled everything on the map that I could find. Included is the OG creators .vmf (map) files that can be opened in hammer. As well as a decompiled version of the map (GMAD extractor). Using a program I've included you can mass extract all of the textures from the materials folder.
I'm fairly sure that multiplayer/co-op isn't a priority for DT right now. So we could be waiting a very long time, but even so, I agree and think this would be a neat concept.
(If you're that desperate you could bribe lucas with 900 dollarydoos)