Just keep your eye out for some spare wheels. 15-16" wheels from a Focus, contour, cougar will all work. Smaller the wheel, generally cheaper the tires. New snow tires for a 15" will cost less than $80/tire compared to 130/tire for 17", not to mention some shops charge more for mounting a 45 series...
On the plus, you at least have a good set of all seasons on the car now. That is a lot better than some mid grade half used tire. Just keep looking for a set of wheels to pop up.