Do your research first, but say "for me, the goal is for this to be a learning experience, however I prefer to be compensated at the competitive market rate" (know what that is). That way, it puts the ball in their court, but you generally know what the answer is and you can defend it. It also makes you look more professional for researching this in advanced. As an intern, you'll probably run into trouble if you ask for too much, but asking for the equilibrium seems fine.