A Ludwig Loewe, cased with all accessories, in like new condition, would probably cost around $50k or more. A DWM, in poor shape but functional, and just the gun, could probably be had for $6-8k.
If you are lucky enough to find one, don't fire it or if you must, use light loads. I have seen one that had a broken toggle due to firing Russian 7.62x25 ammo in it.
Also, dis- and re-assembly is tricky, not many instructions are out there and some are wrong. It is easy to damage the gun if one does not know what one is doing.