I thought the P-9 front sight was machined integral to the slide like an EAA? Does it have a removable front sight? If so how is it installed? Dovetail or what?
These kind of parts are difficult to come by. I had the same problem recently on an AT-84 that someone had filed the front sight bleep near off. I put a Millett for a Hi-Power on it.
My recommendation would be to determine what height you need by some easy jury-rig temp setup and put a Millett sight on it. Probably would require milling or filing a flat on the top of the slide and drilling two 3/16" holes for the studs on the Millett...best done on a milling machine or you might find a gunsmith that has the Millett drill jig. The good thing is that Millett makes about any height or style you want. Plain, serrated ramp, orange insert, etc.
Sight is easy, hard part is finding a gunsmith that 1) can actually do the job without ruining the pistol. 2) He doesn't charge more than the pistol is worth.