Here's what we don't know: what's the overall condition of the Cobalt? How well has it been maintained, and what is her driving style? Any significant rust?
If the Cobalt is generally okay besides needing the struts and front-end work, fix it for now. Everything said here about the crazy used-car market and about used German cars is true. "Out of the frying pan and into the fire" comes to mind about replacing the Cobalt with the Audi.
