Hi,
When I worked at the 4 Queens, different people actually came up with the ideas and they were taken to the manufacturer for final drafting. (Chuck Smores, for example, was responsible for a mulitude of 4 Queens chip designs.) Guess they come from everybody at one time or another? The limited chips sell out as soon as they hit the casino cage usually! (There isn't usually a limit to what you can buy but that is reserved by each casino to decide.) Once they figure out you want them for business it's even easier because it's great advertisement and solid profit.
Cheers!
Ammie