Most I've seen today are Pewter. It would be nice to find Germain Silver (nickle/brass).
There are a couple Independents casting with real Silver but, too much $$$!
Track of the Wolf used to have a small selection of it in their catalog but, I haven't bought a new one in several years so don't know if they still do or not. Crazy Crow might be another place to check.
I just google'd indian trade silver and an actual company named Indian Trade Silver came up. and also Grey Owl Crafts and maybe a couple more. seems to be a pretty good selection at both places.