"Building" powers fast using spells?

[The Sundered Sky]

Instead of building Magic from Advantages, how about building Powers from Spells? How much should the cost of the "spell" you were using for the base increase? Percentage wise. Like the increase per point of spell?

Let's say this could be used for pick up games, last minute game substitutions, easing in newbies, lack of prep time, etc. Especially for a Supers-esque game.

For this, we'd ignore the prerequisite spells tree. The spell list would be seen as another fast source of powers already written out.

I realize this is a lot like the Knacks from 3E. But if we use a spell the way most Advantages are used, that's going to require a lot of Fatigue points. So I'm curious if there's another way to do it. More direct perhaps.

[Culture20]

I think there’s a perk for one-spell magery. Can’t recall the name, but was either in GURPS Thaumatology or Religion.

[Kelly Pedersen]

I'd suggest checking out the article "From Skills to Advantages", by Sean Punch (a.k.a. Kromm, the line editor for GURPS), in Pyramid #3/44. It covers converting a skill to an advantage, and has a box ("Spells?") for doing so for spells as well.