http://skyrim.nexusmods.com/downloads/file.php?id=13166 replaces typical enchantments that reduce spell cost with ones that increase spell power. Also, it scales the effectiveness of magic based on how many perks in that school you have. You should read more into it, if nothing else you can download it and find out for to make the enchantment you wanted.
It's funny you mention it, because I found exactly that on my own. Now, my problem is I can't quite figure out how to reproduce it, or at the very least reverse-engineer it.
Any idea how to do that? Transfer an enchantment from one mod to another or something?