Check these out for replacement key options:
- needswings.com
- sosdiagnostics.com
I've even seen ebay listings for simple non remote/fob plain keys.
Some compared the cost of a replacement key to the cost of buying a set of replacement tires for the Crossfire. When I bought my 14 year old 06 Crossfire last year with 4,700 miles on it one of the first things I did was purchase a new set of tires.