I won the eBay Nevada chip for about $60. Value is very dependent on location and casino. Error chips from LV strip casinos can easily bring over $100 (for example, the Caesars Palace $5 with wrong number of inserts).

Also, I value error Paul-son chips more than BudJones chips. Their QC seems to have been better and fewer errors got out. There are also more things to go wrong with BudJones plastic chips as they are molded in two parts and it's easy for one device to break off or not get filled in the mold.

I watch for Nevada errors, but have only been able to collect a half dozen or so. Always interested in new finds.