Puerto Rico, like many areas - California for example, does not have any requirements for obsolete casino chips. So when a casino closes or changes the rack, they can do whatever they want to with the old chips. In many cases when the casino closes, the chips are sold off very cheaply, just like furniture and fixtures. This has happened with several Puerto Rican casinos and California Card Rooms and Cruise Ships and Nevada casinos (like the Dunes).

Did I leave anything out? Oh yea. Atlantic City. AC Gaming Control requires all obsolete chips to be destroyed. I only know of one instance of a horde of obsolete AC chips and that was when those entrusted to destroy the chips did not do so. This situation has been rumored and not confirmed.

So there are quantities of chips from several PR casinos. I know someone who bought 1,000's of PR chips for pennies a piece. But, there are many more rare and hard to find PR chips. Right now you can get the best deals on the good PR chips, if you know which ones they are, because the whole market for PR chips has been tainted by the hordes.