I volunteer at a charity that reconditions unwanted/discarded bikes and resells them cheap, or donates them. The sales pay for the work. Very often, the only thing that makes them economic to repair is the fact that we have a large stock of used parts that we have taken from other bikes that weren't worth fixing.
You're looking at a complete overhaul. If you have to buy the parts new you are probably going to spend more than the project is worth, I'm sorry to say.