There are several models available on E-Bay. If you type in SLK roll bars they should come up. These will fit a coupe. Let me know if you go this route as I have instructions and a template for cutting the bulkhead. That said I'm not sure these would be considered for track use. They do bolt up to the metal frame in the bulkhead. I would suggest you stick with the $149 bars. The ones I got which were a gift ($49) have to be cut for them to fit.
There are companies that make full cages, my son knows who they are and I will get back to you on that. He had one in his RSX. He's on fire duty this evening, when he gets off I'll ask where he got his. Not sure if they make one for the Crossfire.
Pat