Thank you for the offer Critt, but you really don't need to go to that expense, I have all the sculpting tools I really need.

Usually household items (toothpicks, pens, etc) are just as good if not better than more advanced tools. But thanks for the offer. I have Spring Break next week, so I hope I have time to at least finish the front bumper of the car as well as the other door panel.
I must have looked over it before, but there won't be a problem hardening the Sculpey on the front end. The entire front bumper is Sculpey clay, so there won't be any issues regarding boiling. I'll just put the model in the freezer to cool the plastic, heavily boil some water, and dip the front end in the water. Shouldn't take more than 1 minute to get a durable-enough-for-mild-sanding shell hardened.
I do have an issue in that I may need to remove the front bumper I have sculpted, because the Camaro's rear bumper has pegs that go through it to hold it on. Therefore, I will have to take the model apart to remove it, and I can't do that at present and will not be able to after boiling.
I do have a question though; what grit sandpaper should I use? And where do you buy sandpaper? (specific store would be helpful, ex: Autozone? Home Depot?) I'd imagine my 400 grit I already have is too harsh. For my old action figure sculpting hobby, I used a low powered dremel (AKA an electric rotary manicure tool) to sand items, but that won't work for a completely flat finish. It will help define the grill, but can't be used on the door panels...