Go to Botach.com. They have five pack OEM Glock mags shipped for $100. Cheaper than used in the classified section. They also have the 33 round mags for $30 each. If you were closer to Mishawaka you could buy them from Midwest Guns for the same price until 12/31/2014.
I would consider a nice light for it and a good holster from Henry Holsters. Then get lost of ammo to shoot cause it's a blast to shoot and way more accurate than those other whimpy brands.
I've looked on the website... do you have a direct link to the 5 pack & the 33 round mag?