Here's a bit on a small Montana town that wants its unused prison to house some of the world's worst terrorists.
I figure the calculus is as follows:
Cost of housing Gitmo detainees: $X
Cost to Hardin for housing Gitmo detainees: < $X
Benefit to local politicians behind the arrangement: Priceless!
It's also interesting to note that it's the local, not state-level, politicians that are in favor of the move.