You realize you unwittingly said something that would totally tick a figure customizer off, right? I've heard it's not exactly a cheap hobby. The paints, molds, clay... all that does kinda cost a fortune. Not to mention the man hours putting it together.
I used to be on a M.U.S.C.L.E. board, and someone was selling custom figures made out of special kinds of plastic. He sold them for something that sounded insane for a small minifigure armyman type thing, but it was justified because the special plastics and silicon for the molds was hyper expensive.
I'd say the cost of these figures is justified in so much that, if you were to try to customize these things yourself it would probably work out to slightly less than what they're charging. Remember, retail toys, even though the price has gone up to a shockingly high degree, they deal in selling massive volumes where the molds and prototype and license pay for themselves as they usually expect several thousand units to sell. And if they don't, a big company can take a loss and just sell the remainder to clearance outlets. Big difference, there.