If money is tight for you, my advice would be that you pass on this snake. Yes, it's a sad situation for the animal, but unfortunately, you have to your personal needs first. While it could be an RI and may be easily treatable, there could be other issues that you may not know until you visit a vet... and by that time, you're already into the animal a few hundred dollars.
Don't get me wrong, if I had the money and space, I'd probably have an animal farm for stray cats and dogs and anything else nobody wants to care for anymore... but if you don't have the means, sometimes it's better to pass. Maybe someone will come along that can offer it what it needs. Maybe not. It's a sucky truth, but it is what it is.
***EDIT - Deborah replied before I got this typed in...She knows best.