Free: Contests & Raffles.
Wadu1 beat me to it.
I was given a set of lodge pans when I went to college and like a young idiot let them sit and rust for a few years before I learned to cook like a normal human. I had fantastic results restoring them in an every-day self-cleaning oven. Basically cooks the rust to ash, then you can wash, coat with canola oil, bake as high as your oven will go until it stops smoking, and let it cool in the oven for a couple hours. Repeat the oil/smoke/cool cycle 5+ times until they look beautiful. Time consuming, yes, but simple as can be and I now use them all the time. I've read linseed oil is the best, but I was broke at the time and canola oil did just fine for me. Just make sure whatever you use has a smoke point as high as possible (as long as your oven will get beyond that smoke point to cure it on). Good luck!