I don't think you are going to find very many high round count PM40's out there. I have maybe a 1000 rounds through mine and it was used "some" before I got it. It will be years before I change anything in it. Your 5000 round count should be a good starting point for the recoil spring and maybe the magazine springs.
Joe
Kahr CM9 9mm, Kahr PM40 40cal, SIG x-Five All Round 9, SIG P226 9, 40, and 357Sig barrels/slides, SIG P239-9mm, Desert Eagle 1911G, CZ75B Da/SA converted to SAO and Kadet 22 slide