There are a number of exceptions to the "face value" valuations though.
Just 2 of many examples --
Paris $5 Millenium chip -- brings $25 to $30 or more, almost all the time.
Main St. Station $5 "Mucha" series of chips brings a premium.

The Chip Rack does list all Nevada chips, including commemoratives. There are other price guides for other states which include commemoratives too, though not always up to date. Colorado, Riverboats, etc.