Not to sound like a dick or anything, but it's called a magazine. A clip is used to feed ammo into a fixed magazine.
Try looking for mags by Mec-Gar if you want shooter mags. If you want some for collector value or to enhance your rig, you'll pay between $75-300 depending... Mec-Gars should run about $30 or less.
Sportsmans Guide sells them, as does many of the usual gun gear places.
Try this...
http://shop.sportsmansguide.com/net/cb/cb.aspx?a=55867
or this...
http://shop.sportsmansguide.com/net/cb/cb.aspx?a=282546