I've been told by a couple of people if you get out of metro-Denver area that veterinarians charge a lot less. One guy said his dog's cancer treatment was going to cost over $2000 here in Denver. He was able to get the same treatment in Pueblo for $400. He has a sister there to help. If it isn't a emergency situation it might be worth calling around.
This is just hearsay, not personal experience.
Hope your cat buddy gets well.