NIH trainee pay scale: http://grants.nih.gov/grants/guide/notice-files/NOT-OD-12-03...
Depending on the institution, you may make slightly more than the minimum (starting at $39K), but postdocs in the sciences do not 'typically' make $50-$60K. As a monetary investment, academia is about as poor a bet as you can make: spend 5-6 years making ~$25K then another 3-5 years below $50K. Then you might be able to start making professor money if you're in hot field and willing to sell your soul to your work.