As noted above, having all the numbers match is important. A non matching pistol will be worth about half as much, and that's true for both the P.38 and the earlier P.08 Luger (regardless of the pattern).
Matching number magazines don't actually add that much value, although sellers with matching magazine want a premium for the pistol.
On a P.38 different grip styles appeared based on who made the pistol and when it was produced, and the correct grips are important and will add to the value. Your pictures are too fuzzy to tell what you actually have, in terms of the 4 digit serial number and suffix code. The suffix code can be used to determine fairly closely when it was made, and if you post the serial number and suffix code, I can tell you when it was probably produced within a month or so.
Walther made "AC" marked pistols tend to bring slightly more than Mauser made "byf" marked pistols, which in turn bring slightly more than the "cyq" marked Spreewerk pistols.
If you have the actual bring back paperwork with the pistol that will increase the value a lot, as it establishes a provenance for the pistol which has a great deal of appeal for a collector.
As it looks right now, the finish and condition isn't bad, and it would easily be a $750 to $800 pistol. Pretty much any shootable wartime produced P.38 in very good condition will bring at least $500, just for it's value as a shooter. The post war P.38s with alloy frames and the later P.1 marked pistols tend to bring a lot less money unless they have a very solid and collectible provenance, and you can still get an alloy framed post war P.38 or P.1 in excellent condition for not much over $400.