RI's can be highly contagious. A few years ago I almost lost my whole collection (about 15 snakes) to a horrible RI strand that a new snake had bought that I had in quarantine.
I'd be looking to be spending at least $100 at a herp vet. In the mean time, you can let the snake soak in some warm water with a top over the container. The warm humidity will help loosen up the mucus and help the snake breath a bit better till you can get it to a herp vet. As Robin said, your snake needs to see a vet to get treated from it's RI. RI's don't just go away.