What is your definition of affordable? Compared to NorCal prices for example it is still dirt cheap. In any of the 3 towns for $300K you can buy a decent home, $500K a very nice home. That same $300K-500K in the Bay Area will get you a closet (maybe).

One thing to keep in mind with MT is the insanely high state income tax. Sure there is no sales tax, but if you make any kind of serious income, you'll get hit pretty hard.