I was at his place a couple of times during that time frame.
As for cost, in the early '70s who would have imagined what value a COPO would eventually make. By the early '70s a '69 COPO Camaro wou have been raced out and not worth a great deal.
For comparison I bought a 1968 Olds 442 Convertible, 455 HO, Muncie, Posi, W31 Air intake etc., etc. I bought it from a DB Motors in Leicester for about £1700 in 1972.