Take a look through the FAQ sections, Martin has given you good starting data. It looks like someone polished and reblued it, which would make it less of a collectible (so-called 'shooter') than an originally finished piece. Beware of the P38 fever though, you may have to get one from each maker, era, etc.
OK, refinished/reworked as mentioned before. We can narrow down the yom to November/Dezember 1943 (SN + n-postfix), WaA 135 was the number code of the Wehrmacht Acceptance Office (Wehrmacht Abnahmestelle) at the Mauser plant during the production of the pistol. So it's a genuine German Wehrmacht P38.
At that price, you still got a good deal! Collectors might turn their nose up at refinished pistols but a P.38 with a steel frame in working condition, still has authentic war time history going for it.
If you do decide to shoot it, have it and the magazine closely inspected for function and damage first. Then after passing muster, do not shoot hot ammo in it!
So you have a "way too pretty " P.38, that you can enjoy shooting (maybe). That's a bargain for $275!