COPOs 9560 & 9561 were COPOs for a reason-they were special orders involving non-RPO equipment that required engineering involvement. Legend has it that a minimum run of 50 cars was required for a COPO proposal. Once that hurdle was cleared and the COPO was approved other dealers could and did order them. I believe both Fred Gibb and Don Yenko assumed they had exclusive rights to their respective COPOs. Chevrolet ended up taking back most of the Gibb ZL-1s; Yenko stated in an interview they had a very hard time selling them.
So technically any dealer could order either COPO. The most expensive ZL-1s were the two Rally-Sports #55 & #68. Docs for #68 indicate a list price of $7919 about twice the price of an average Z/28 at the time.
This was not a well-managed program. Gibb was told the COPO would cost about $2000; final list price was $4160. Gibb couldn't sell them and by May '69 37 of them were sent back to Norwood. However at the same time another Chevy dealer in Illinois 65 miles from Gibb ordered & received two more; Orange and Silver 4-speeds just like other ZL-1s wasting away on Gibb's lot.
http://www.camaros.org/copo.shtml