A couple years ago at El Cortez I told the cashier that I would like to buy some old chips if they had any. She relayed this to the supervisor who brought out a rack with a few loose chips. I bought a few $5 and $25 paulson with metal inlay.

In Caesars, check the cage in the high limit room. If you get the right cashier and they're not busy you might find some really nice old chips.

In the past I've gotten some really nice old chips from the cashiers at Golden Gate and Jerry's Nugget.