From a January 6 entry at the Jawa Report:
After reading this Bloomberg story about Gitmo inmates being released and returning to the battlefield to fight or even blow themselves up on Baby Jesus's birthday, I think I may have have [sic] determined that we've overlooked a crucial and economic solution to the problem.
Most if not all of these men were captured "out of official uniform". Under the Geneva Convention that makes them all spies and they may be be [sic] er uh, shot.
The site above prices 7.62 mm rounds at 5.99 per 20 rounds.
All 198 remaining detainees can be effectively dealt with for 59.99 + shipping and handling. (less if you're willing to use a smaller round)