I just wanted to share a new source (at least for me) with everyone.
I ordered a 12" x 6" x .125" sheet of brass from
http://www.cut2sizemetals.com/brass/to use for side plates. I thought the shipping was a little high. But it came today and instead of
12" x 6", I got a piece 18" x 8". That's exactly twice as much brass as I ordered. I've got about a lifetime supply of sideplates.
They have a little check box on their order form "Customer will accept larger piece if available for same price" be sure to check it. A good deal, I'll be using them again.