Cheapest place to get tires?

I have a Mercury Sable 95. Tire 15" Rims . Need a 205/65 Tire. Where is the cheapest Place to buy? Can be new or slightly used... Just need them to get me through the next couple of months because I am saving up to buy a new car in the Spring. My tires now are completely shot but don't want to spend much on tires that I will only be using for a couple of months, Anyone know any deals let me know?