After hearing about the existence of Duck's Sheet Metal from my office mate, I stopped in to see how much they would charge me to cut my 150 armor squares from 16-gauge aluminum. The alloy is something like 3008, and evidently it's very workable, so it's the only type they sell (they do lots of brake bending work as well). The cut fee and materials fee are literally 1/5 of what Online Metals wanted. Needless to say, I was delighted. I'm picking all that up next week. I forgot to order the bands for the back of the armor while I was at it, but I can always do that later.
I'm wearing my skinny pants.