James Campiglia's US Price Guide may be your best single guide. It has a lot of Nevada, but also covers the other gambling states. It gives you price guidelines with adjustments for condition. Nice pics, too. http://www.nevadacasinochips.com/USCasinoPriceGuide.htm

If Nevada continues to be important to you, The Chip Rack (TCR) is essential, it being the comprehensive listing of all Nevada chips. Price rating included. The TCR numbering system is the accepted standard for Nevada Chip. http://thechiprack.com/

then there are a lot of more specific guides. CA, WA, cruise ships, FL, illegal, etc etc. The Gaming Table is a reference book of ALL casinos worldwide (with a mention of the types of chips they produced) -- good for tracking down mystery chips.

I started with the 1st 2, then picked up a few relevant specialty guides as my collection warranted.

GL

Mark