They convert the new Camaro into the bandit Trans-Am. You buy them just like that though.
Anyhow, buying something right off the factory production line is the best and most convenient method. You don't want to buy something brand spanking new, send it off to another company and wait another month or two for them to get it done, and then you get to drive it.
But that was just posted to be looked at just in terms of styling. They even developed custom modern snowflake wheels.