Bitmit.net ... saw 50 of them sell the other day for $250 ($5 each if my maths are not failing me...), also have seen several on auction at sub 0.1 BTC prices as well.
$5 each is nice for a test, but I suggest buying only few because if you have over 10 your HUB might get problems how to run them all.
I suggest only getting 1 to play around. It won't ROI
