No one knows. GM didn't keep this kind of record. However, for 1968 there were a total of 272 L89 Camaros built.
In 1993, the old United States Camaro Club published a breakdown of Coupes -vs- Convertibles in thier official publication, "The Camaro Enthusiast". In this issue, they state that of the 272 1968 Camaro's with the L-89 Engine Option, only 20 were Convertibles. Just where they got these numbers is unknown, so take it with a grain of salt.
As for value, anywhere from a few hundred dollars for a stripped parts car to 100K plus for a restored example.
Ed
