jbone84 - i haven't tried any aftermarket mags in my P238, but I bought some Sig mags from Top Gun Supply for a cheaper price than Sig. Also, for an IWB holster, I got a Desantis Cozy Partner for the P238 (Cozy Partner 028). It's a really comfortable, well-made, conceable holster. The P238 is so thin and light and a breeze to carry.
I just put over 250 rounds through my P238 again this past week. What a great little pistol!