http://www.casinorarities.com/
Check out our Hall of Fame to see rare chips that you don't see around often. Many of the hobbies top collectors have loaned us their chips to picture.
Did you see the gambling museum while at the Trop? And Nevada Mint gift shop?
I wrote the "Official US Casino Chip Price Guide" as noted in Charles post above.
This board is a big help too & as you see there are many ready to share here. It is a great hobby & has grown a lot in just 10 years that there has been a National Club.
Good luck collecting & have fun.