When a casino closes, it generally sets a redemption period for outstanding chips. Depending on the regulations in that state, it can be quite short. In New Jersey, a reserve is set aside under state law and technically the chips always have redemption rights at face value. And exception was imposed for chips that had been "destroyed" and were later found.

After the redemption period, prices can vary, but for the most part $1 chips seem to keep at least a $1 in value, while higher denominations lose substantial amounts of value. $100 chips can be found for as little as $5.

These observations are generalized, and limited to recent chips (like the past 20 years). Older Las Vegas chips can have substantial value, and the closing of the casino only seems to add to that value.