Would a $2 tax line be a better idea than a spending limit?

They have this kind of tax (I believe it's called a luxury tax) in baseball. It doesn't work because if teams can afford to overpay for players they can afford the tax. Case in point: The New York Yankees, who paid over $70M in luxury taxes from 2008-10 despite leading MLB with a payroll of over $200,000,000 each year.