I’m thinking of trading my M41b sniper or selling it to try and get a nice Luger  in 9mm. I see prices of Lugers these days vary pretty significanty without much difference ( to my untrained eye) in the gun . What are some things to look out for so I don’t get screwed ?

Not sure what you have in mind, but 2500 should get you a very nice piece,
Iv been looking at getting a Swiss Luger, i just wish the Swiss was in 9mm.
If you are buying make sure you check all number including the firing pin, if they wont let you take the gun apart then walk away,  also some people try to pass re finished guns as original finish guns

Do you want a shooter grade non-matching but fun to shoot the barrel out of or a collector grade that you might never shoot, but collect and display it? From what I've seen a shooter grade can be had between $800-1200 depending on shape and how many mismatch parts are used.  The more matching a Luger is upto being a complete match will shoot the price way up. You will normally pay a premium for Artillery (long barrel) Lugers even if they are mismatched. Also note that Luger's do have a lot more parts than other handguns, so it can be a bit harder to find a complete matching one.  All of my Lugers are from 1915-1920, and I often see a lot of Lugers made between 1910-1920.

Buy from a reputable dealer. If you're looking for a $2500 Luger and are asking what to look for, you NEED to buy from someone with a spotless reputation. There are LOTS of force-matched Lugers, or ones with counterfeit markings that only an experienced eye will catch.

Thanks , I’ve been looking at Simpson’s , still not sure on what I want . Really torn on the different models . I think I’ll buy a Luger book and read through it before buying , I might also go lower on my max price. Might not want to blow all the cash I get from the Mauser on a Luger.