Those are stock dell stands. Less than 15 bucks on ebay.
Ergo 3 monitor arms are overpriced and wont fit a 30". I know, I have 2 DS100 Ergo 4 monitor stands.
Actually the best place I have found for a *cheap* but effective stand that will fit a 30" and 2 monitors flanking it is http://shop.easymountlcd.com/ or http://www.tykesupply.com/
The best way to flank a 30" is with 2 20" 1600x1200's mounted vertically. Read about it here: http://en.wikipedia.org/wiki/WQXGA#WQXGA_.282560.C3.971600.29
This will be my next at home setup, once I pull the trigger on a 30" and 8 new monitors at work to free up the Dell 2007FBp's I have.