http://kff.org/interactive/subsidy-calculator/
examples:
~ 40 years old, $45k income, lives alone, smokes cigs, no kids = $330 per month, no rebate from the Gov.
~ 40 years old, $45k income, lives alone, NO cigs, no kids = $300 per month, no rebate from the Gov.
~ 53 years old, $75k...