If you want a collector's item with all the Nazi proofs and etc, in good condition, expect to start around $500. That seems to be the starting point here in the Southeast. Last one I saw was a vet bring-back, in very good condition with all marks intact, overall VG with a Excellent bore, complete with holster and extra mag for $600.
If you just want a nice P-38, the ex-German police models are now coming into the country and can be found for as low as $300 if you look around. SOG, J&G Sales, AIM Surplus all have them in the $300 range.
Ken Strayhorn
Hillsborough NC