Poll: Would you pay a developer who is 3x as good as average, 3x the salary? 15 years ago
Yours sounds like a question assuming all people can build all software. That is simply not true. Sure, if you want to build some enterprise software with open source tools, hire an average bloke with XP and TDD experience.
I would pay someone 3X the salary to someone 3X "above average," but that does _NOT mean that s/he would accomplish the work in 1/3 the time at the same quality.
The difference between _brilliant programmers and average programmers is MASSIVE: someone 3X as "good" needs to be paid 3X the salary because they can create something new, imaginative, life-changing.