Got a pm recently from someone looking to start making reelfoots asking about reed materials, and thought a thread on sources might be useful to all of us. I'll get us started with sources I've found.
.005 phosphur bronze shim stock, in rolls - amazon.com
.005 steel shim stock, in rolls - amazon.com
.008 phosphur bronze, in sheets (sold as .006) - hobbylinc.com
32g nickel silver, in sheets - firemountaingems.com