Agree, do not skimp on the cage. You do not want to be one of those people who have to rip it out and thrash all friday night to build a new one. It happens more than I think it should. Cages can be rejected for a number of reasons, from bad bends, bad welds, or bad fitment to the car. If you are not comfortable bending/welding then either pay a shop, or find a team local to you that's willing to help you out.
I'll also ask, how smashed is smashed? Rules require that you have OE crash structure, if that's obliterated, probably not worth it.
Make sure you can fit in it as well. Like most fiberglass/composite cars, you can't mount anything to the floor. You will need to use the factory seat mount locations. The upside is that its a pretty roomy interior but once you start adding the main hoop and door bars, the space will disappear quickly. The C5 floor is basically balsa wood wrapped in a plastic/composite. You can't rely on it for anything. Every single bar mount has to go to the frame or another bar.
You also need to be very careful working in the area behind the seats. The gas tanks live there. I've seen people try to mount things to that cross beam and put a hole in one of their tanks.If I were to build ones for Lemons, I would try to put in a fuel cell if possible. The dual tanks can have issues with delivery. The fuel pump delivers fuel to the engine and uses a siphon effect to pull from the other tank.
1992 Saturn SL2 (retired) - Elmo's Revenge - Class B winner, Heroic Fix winner x2
1969 Rover P6B 3500S(sold) - Super G-Rover - I.O.E Winner, Class C Winner
1996 Saturn SW2 - Elmo's Revenge (reborn!), Saturn SL1 Dazzleshipm Class C winner
1974 AMC Javelin - Oscar's Trash heap - IOE,”Organizer's Choice" and "I got Screwed" award winner