What's currently available for Contour springs is summed up fairly well
here. <clicky>
As BrApple pointed out, the likelihood of finding springs from another platform with the correct rates, free lengths, and wind finish diameters that will fit the Contour spring perches is slim to none, and well, we know the rest of that metaphor.
In a spring swap/suspension upgrade, the cost of the springs is secondary to the cost of new struts, new upper mounts and (front) spring perch bearings. Do the work yourself and the labor cost is your time, paying someone else to install the springs and other parts is likely to be 50% of the parts cost as labor. If you want full benefit from better/different springs, you need to treat it as a system upgrade, or the results may be disappointing.
What do you want from the car? Better street manners? Smaller fender-tire gaps? Capable autocross or open track warrior? Bodywork-scraping-the-pavement-jiggle-mobile? Different goals require different paths, parts, and amounts of money.
