You're right, They do have value, There are many sites that buy and sell these "Play Chips". I don't know if its allowed, but I will try this....
:: AliensHouse - PokerStars Chips and More!! :: (This site is ran/owned/operated by one person, never too full to buy, always sells low price, and is very friendly, Best of all, online about 18 hours a day.)
Check them out.
Sorry if its not allowed to link.
(use google, clieck search " AliensHouse " click i'm feeling lucky.)