Can't tell if that's a good thing or not...? Anyway, a wizard has to pay for copying spells to his book, so it's not that different. Might even have to pay for the scrolls if he can't find them. The cost covers the materials required for the application.
What's more important is that I haven't set the prices in stone yet. If you think lower prices would be more reasonable, I'll change it. I just thought that since you actually construct something into your body, you'd have to provide the materials, and good materials ain't cheap.