Incidentally SF is the cheapest position salary wise. The most expensive SF out there only has a 160k salary.
That lends to the notion then that these high salary C's the OP is referring to are 1-3 skill wonders. As the SF has more skills needing training, hence more training time, it probably limits the skill level achieved. Whereas those C's might just be trained in ID, IS, and Rebounding their entire life. Give me a well-rounded C that can fill in at PF, rotate out to contest a shot, and knock down the occasional 3, any day of the week, and I'd be a happy man.