Here's an ebay link to a good ps to start with.
http://cgi.ebay.com/MASTECH-VARIABLE...QQcmdZViewItem
Wouldn't go any smaller, but if you can afford to go bigger i would go for a 20amp Mastech. Just search for "Mastech power supplies" on ebay. I have the one in the link and I really like it.
Radmaximus