The link is in your message again . As far as error chips go...I only have one { if you want to consider it an error }. I have a Circus Circus $5 Super Bowl chip. Even though the words Super Bowl belong to the NFL, gaming passed the Circus Cirus chip. Once the NFL found out they wanted all the chips returned & destroyed { or something to that effect }. As far as value goes I think it would depend on how much you would want an error chip and the price you're willing to pay. Would I pay a high price for an error chip....no. Would someone else who collects error chips pay a high price...probably. Once again, in my opinion Error chips are only worth what someone is willing to pay. As far as a formula...I'll let the more Knowledgeable collectors give their opinion.

Victor