A once found a large package of white goose biots at Michelle's craft store for under $5. I bought the feathers and several colors of RIT dye and experimented in small batches of about 1 cup of water heated in the micro-wave. This is plenty to dye 4-5 biot feathers.
I made some odd colors but I did end up with a good supply of usable stuff in great shades.
Unfortunatly I have not seen the bulk goose biots for sale since then.
RIT has a web sight with color charts.