I don't think I really follow you here. You have a point-buy system, and you're trying to balance damage against cost?

That said, if you're doing what I think you're doing--trying to construct a unified set of guidelines for power creation--I really would suggest starting from a base of Mutants and Masterminds. The system is flexible enough to manage just about any ability you can imagine, and the overall balance and math are about as good as you can expect for that sort of thing. When I was my d20 Exalted hack, I started off by building each of the basically-spells as M&M abilities and working out their price. I used those numbers to sort them into three broad tiers of cost, which became sort-of-spell-levels. Maybe an approach like that would help?