Susan,
There are some state chip guides that have information on Indian Casinos.

Colorado Chips & Tokens, Allen Barrick
Casino Chips of Washington State, Steve Goodrich
Florida's Gaming Chips, Checks & Tokens, Mark / Myrna Lighterman & Robert Ginsburg (2 voumes)
California Chip Price Guide, Mel Jung & Armin Pfaender
Eastman's Illustrated Guide to California, Larry Eastman.

Ordering information for some of these is available on the Chipguide.com

Paul Donohue