I just paid $120, which included the initial examination and diagnosis, and 5 injections of Baytril. This is my first time ever dealing with this, so I have no idea how this price compares to others.
I would definitely go in and get things checked out. I thought I was overreacting too, but it turned out I wasn't, and because I acted fast the vet said things would be much better for the snake. The way she explained it was this:
Animals in the wild have evolved to not show any signs of weakness. The weak and sick are the ones who are preyed upon. They hide or mask the symptoms as much as possible. This means that by the time they start showing symptoms, it's because they simply can't hide it anymore, and the sickness has gotten quite severe. Better to nip it in the bud, because by the time the BP starts blowing bubbles and really gurgling, the RI has progressed to a level that is much more difficult to overcome.