Alex I think if you check on the other CF forum in the U.S. you will find a lot of vendors now making these available for a reasonable price. For instance, there is a Canadian vendor in Concord ON. making real carbon fiber splitter and side skirts available for $1,895 U.S.. There is still shipping and installation to deal with after that though.
If you order a stage 1 Z06 you can order the GM aftermarket parts to move the spoier to stage 3 for about $500 U.S.. This would be for the Carbon Flash version, like the OEM Z06 one.
I am not sure if the Z06 splitter and skirts can be fitted to both a C7 Stingray and Z06, you would have to check with the particular vendor.