http://www.camaros.org/copo.shtml
"The telling blow for COPO 9560 was the price. Gibb is quoted as saying he believed the cars would list for around $4900. Unfortunately for Gibb, the new edict at Chevrolet came through that options had to be priced according to production costs. Just the "HIGH PERFORMANCE UNIT" option was priced at $4160.50. (For reasons unknown, subsequent ZL-1s were priced at $4160.15) The mandatory power disc brakes and transmission option pushed sticker prices over $7300. This was far more than a well equipped 1969 Corvette and would be roughly equivalent to today's Z06 Corvette. Not only would the cars not sell, Gibb likely was unable to pay for them. Gibb plead his case, and in an unprecedented move, Chevrolet agreed to the return of many ZL-1 Camaros. The cars were shipped back to Norwood, Ohio beginning in May 1969 and Chevrolet began to shop the cars around. Gibb also wholesaled cars directly to other dealers who would soon learn what he knew: they were sale-proof. Many dealers removed and sold the ZL-1 engines, replacing them with iron 396 or 427s, adding stripes and mag wheels, doing whatever it took to sell the white elephants. Several were stolen and never recovered. Gibb sold his last new 1969 ZL-1 Camaro in 1972 (with the aid of a $1000 rebate from Chevrolet). It was re-possessed and returned it to Gibb in 1973."
"Fred Gibb may have believed the ZL-1 Camaro was his exclusively. Compounding his difficulty in selling the cars was the fact that other Chevrolet dealers had learned of the COPO and ordered 19 additional ZL-1 Camaros. Some of these cars had more optional equipment. Many of these Camaros found the same cold reception as the Gibbs' cars and suffered the same fate: engine swaps, theft, modifications."