Not WW2, postwar. The slide marking style and the fact that it lists Ulm as the factory (instead of the wartime plant at Zella Mehlis). More might be said if there was a pic of the otehr side, acceptance stamps and/or a better resolution to see what serial range you have.
Walther did make P38s after WW2, up to the 1960s I believe.
A lot depends on condition but for a commercial P38 in 9mm made between 1967 and 1975 anywhere from $400 to $800. More if it has a steel frame or high polish finish. Is this one you're looking to buy ?
Just came across a 348xxx with a 1972 stamp, so this one is likely a 1970/71 vintage. Seems to be a standard brushed alloy frame. Redcat's price range is probably realistic; for me more toward the lower end, 500/600 max.
What started as a simple side grip replacement became a lesson on paying attention (or not) as the trigger bar fell out and I cannot determine how to engage the trigger bar with the trigger bar spring. This is frustrating to be looking right at something and not arriving at a...