I assure you, a dozen-odd servos is going to be pretty expensive. Try buying some... guess a fiver each unless you want cheap non-functional crap (as I have discovered.)
Also the setup costs to manufacture the shell by proper industrial moulding will be pretty high. Note their comment about the metal mould. Something like that will be nothing to somebody making millions of items, but for a small niche like this it'll be a substantial risk.
If you want to make a cheaper one, you could try getting six or eight servos and doing what Mike did (I'm tempted):
http://www.raspberrypi.org/phpBB3/viewt ... 37&t=47315