I have a mag carrier from concealment solutions. It wasn't dirt cheap, but it's quality. They come in black, faux carbon fiber, and tan. Think the Black and Tan are $54, Blackhawks makes a dual mag carrier as well for around $45.
I have a G-Code kydex double carrier for my 1911. New is in the 35-40 dollar range (merchant & shipping varies), and its a scallop style and very good, but i have no other brand of double carrier to compare against it.