For me, I spent over $200 on medhelp to in their expert section. I was going to try justanswer the other day but I felt it to was too expensive at the time, somewhere around $55 for one question.
With healthtap, I spent around 200 as well but the funny thing it's only around 2 bucks to get a quick answer, so I'm constantly on there. Most docs are not specialist but just regular MD's. But they are very short and to the point compared to medhelp or justanswer where you get full detailed answers.