unfortunatly when you purchase an animal you take on the cost of caring for them, you should not be so worried about the cost and be more worried about the infection - like beeman said if it is RI it can be fatal and by the sounds of it your spotted sounds bad. Is there no way to get to the vet today? - after hours emergency?. Vets are not cheap so dont expect it to not be expensive especially if she is bad.
she's going to the vet tomorrow but I would like to know what i'm in for....
your in for a rough patch - never mind about the money as a snakes life is worth it!
I should add that most vets will let you pay your bill bit by bit so its not one huge lump sum