The difference is that recreational marijuana costs more than medical, but you don't have to pay for access to recreational. The application fee in Colorado is now $15, and a doctor's appointment will cost between $90 and $200 (according to the Denver Post). I believe Fibro would be considered under the "severe pain" (or maybe "persistent muscle spasms" or "cachexia"?) category.
As for what to do when you get to Pueblo... if you want to access bud through the medical program, the state's website has instructions.
I'm also thinking about moving to Pueblo, so I hope you will continue to post once you get there, and tell everyone what you find.