Finding a fake

[boogieman]

Finding quality guns (all guns not just Lugers) with matching numbers for a reasonable price is becoming more difficult and therefore the prices continue to rise. With modern equipment its not a all difficult to stamp parts to match. Even "honest wear" can be reproduced with relative ease. How do you know you are getting the real deal?
In reality I could have a set of stamps made (if not already out there) and stamp every part in a non-matching gun to match including proofs. Im sure im not unique.
Are we relying on the honesty of others not to force matches? To my knowledge there is no law against this unless you deface the serial number on the frame.
My question concerns newer collectors like myself. How do you keep from paying top dollar for a fake if everything looks as it should?