I found some #26 phosphor bronze wire on Amazon. It is $8 for a 1/4 pound roll. That would be a life time supply for a hobbyist. It is a little large but can be hammered flat or even mashed with a pair of pliers.
They have phosphor bronze shim stock that is thin enough but would have to be cut in strips.
Just a couple of more options.
I found a source for .008" shim stock in phosphor bronze material. A 6" X 12" sheet would be a lifetime supply for a hobby builder.