Hello Clayton, glad to have you at the forum.
There are literally tons of places to look for a shootable Luger.
One of the East German ones would be a good place to start, as would just a mismatched pistol. Auction places are not the best places on the net for a beginner, although you might get a really good deal.
If you came through
www.lugerforum.com look on the left is a Links and Resources, as well as a Classifieds section. Tom Heller usually has a few shootable Lugers, I bought one from him and have been very happy, but there are lots of places to look. Gun shows, pawn shops etc., although many do not know the difference between a collectable and a shooter and will sell you a shooter for a collectable price.