Need help locating parts

I recently bought a 1984 dodge 1/2 ton 4x4 for $500 and am in need of the front rotors. The left one is paper thin and the right isn't much better. I've tried eBay and local parts stores but eBay has only 1 and the local parts stores want minimum of $70 each and I can't afford that right off. Is there a website that has a cross reference or a place to buy used parts for reasonable? I'm only using this truck for getting firewood. So I don't need anything seriously expensive. If this is in the wrong area, please feel free to move it to the appropriate area. Thanks much in advance.

Dirkin