The factory ones are not that expensive. However, they are made by "MEGGAR MAGAZINES." The mags on all the new SIGs are no longer made by "SIG." Go figure. I have seen them in SHOTGUNNEWS for $18 or so. The quality has dropped unfortunetly, but they function just fine. The "FACTORY" SIG mags are essentially "aftermarket" mags on there latest run of pistols.
Good luck.
