These Mec Gar Reproduction magazines are without a doubt the best aftermarket P-08 magazines available. They are superior quality and I bought one for my DWM 1920 .30 Caliber Luger, The link I am providing is about the cheapest that I have found and they ship very fast. It does state 9mm, BUT it doesn't matter, 30 and 9mm Luger Mags are the same. I have Put over 300 rounds through my Luger with this magazine and it has never jammed one time. I have been collecting LUgers for over 20 years and these are the only magazines in my opinion that match right up to the originals.
http://www.ambientsw.com/gs42897.html