... and you can't find one. Why not print your own!
http://defcad.org/ar-15-magazine-30-round-mag/I don't know if anyone remembers this kid from his first attempts to fabricate his own AR lowers with a 3D printer, but he's got a successful design for a standard-capacity AR-15 mag. You can download the CAD file and print it out -- if you have a 3D printer. All you would need is the main spring. The body, base plate, and follower can be printed.
Pretty cool, I think.
