I live in Longmont, near the peoples republik of boulder. I shoot at
http://www.ncrgc.org/, and I think we are accepting new members. Many of the clubs around here have long waiting lists (I was told the wait at one club was 106 years!). There is a public range at
http://www.pawneesports.com/ that seems reasonable. One benefit to the pawnee area is that you can shoot in the pawnee grass lands. All you need is a GPS, and a map of the area. The other range I have shot at is
http://wcfw.org/. Most of the ranges cost around $70-120/year, with some sort of work requirement. The ones I listed are closer to Ft. Collins.