Brownells $10 off w/free shipping over $99. Mags are $29. Add a small filler item to hit $99 or buy four mags.
Said PROMO Codes do not apply to Glock Brand so $30.75 each for 4 magazines shipped to me.
Good luck finding them under $30 each. That seems to be the going rate.
I have close to 100 OEM Glock/HK magazines and do not need any more.