Color Changing Glass - Rocks in a Box 30

I make glass in my classroom.

I've made glass colored with cobalt oxide (dark blue), copper (II) oxide (light blue), chromium (?) oxide (green), manganese (?) oxide (purple), and silver nitrate (disappointingly colorless).

I've not made any glass with neodymium oxide, but I'm thinking I want to do that as my next experiment.

Anybody know of a better, reliable, cheap source of neodymium oxide than these sources? I'll be honest that 1/2 a pound - even 1/4 pound when we're using less than a gram per batch - would last me pretty much forever.