Depends entirely on the P38. An all correct, all matching, unrefinished, unmessed with gun from any manufacturer will sell for around 1k these days for a common manufacture. If you hunt hard you may be able to do better.
Some years/codes are significantly rarer than others. Most common could be mid war cyq guns or something like an ac44 or ac43. I happen to actually collect P38’s specifically and have about 15 or 16 of them. Back maybe five or six years ago I got lucky and bought some more common dates such as an ac44 and an ac42 for between 600 and 700 dollars. I also have things like double matching ac41 rigs, single matching ac40 guns, a byf42, an FN frame cyq, a 480 gun that are worth over 2k or I’m some cases over 3k each.
Basically it all depends. I would suggest you hunt for something like an ac44 that is all correct and see if you can pick it up for under 1k.