A holster specific to the p239 will not fit the p225 due to the square trigger guard. Having 2 mags for the p225 is probably better than one but not at the $75 price tag to source the separate parts at Numrich. At this point, at least for range time, the Promag mags (at least a couple) may be your next best option a la J&G Sales or eBay. Interestingly, Triple K (ebay) also has modified p38 mags for the p6/p225.
Congrats on the gun. I have been carrying mine in a rgrizzle city slicker 2. Highly recommend the rig if you want to invest in a higher end holster.
"You know, Scotland has its own martial arts. Yeah, it's called Fuck You. It's mostly just head butting and then kicking people when they're on the ground." - Charlie MacKenzie (Mike Myers in "So I Married an Axe Murderer")