“Where can I get the cheapest Glock magazines?” is one of the more common e-mails I get. Considering how popular the pistols are, it really shouldn’t be a surprise.
As you may suspect, different retailers will run specials or sales on Glock mags, so prices can and will vary. However, for standard magazines, I typically expect to pay about $25 +/- for new. Online sites like Midway USA and Brownells tend to be solid sources for the mags at this price.
With a little looking, though, you can sometimes do better. Right now, for example, Natchez Shooters Supplies is selling many of the standard capacity magazines for just $19.99. In fact, I just ordered a few more 15 round Glock 19 mags from them. Heck, at that price, it is hard to not order a bunch.