I purchased a few factory made mags from Mag Shack. They are the same as what came with the pistols and are fine. Just make SURE you buy Factory mag's and not after market - IMO.
I only buy and use factory magazines with pistols. I may pay a little more but never have any hassles. The only exception to that are 1911 mags and they are made by dozens of company's such as McCormick, Wilson Combat, Colt (although I forgot who made them for Colt) and a bunch of WWll era USGI mag's that are unmarked. They all work fine however the Colt and Wilson Combat are the smoothest to use and load.