With an FSA, $500 visit costs $100 (20%). But, it's pretax so it's about 30% off that; so, about $70, which is a little more than the average co-pay. My co-worker told me that HSA works best for people who don't go to many doctor appointments. Which makes sense. I calculated that, between both of us, we go to the doctor about 9 times per year. Between my poor eyesight and poor hearing, it may not make sense.