http://www.mpja.com/productview.asp?product=12424+PS http://www.mpja.com/productview.asp?product=15366+PS
A lot of Xylotex users use the power supplies from MPJA. You want to get at least 24V, and no more than 28V. And probably 6a or more.
You can get something cheaper from Ebay, if your patient. I got a 24V 12a for $5. I took a quick look, though, and didn't really see anything right now.
Btw, those aren't 30V motors. Automation Direct doesn't provide that info, but it's most likely 3-5V.