There's collector grade and then there's "shooter" grade. Shooters don't have matching numbers and they have some kind of flaw. BUT... you can shoot them!
If you go in the "wanted to buy" section and say you're looking for a shooter, you'll probably get a few bites. Price is subjective, but you can usually get a safe luger to shoot for $600-800. Also, check gun stores in your area because they pop up occasionally. I just got a shooter for $725 at a gun store in Maine.
Of course, this all depends on if you want a display gun or one you can play around with. I shoot all my guns, and there's nothing like shooting a few rounds from a piece of history!
So rather than spend $1500 on that original one you were talking about, get a shooter luger for $750 and track down a Japanese Nambu for $750!