I have a 15 Amp rivergate for $25 plus whatever it costs to ship. It is not pretty, but it works. It was originally a variable output version, but the variable output side doesn't work (resistor blew or something) so now you just have the fixed voltage (13.xV) 15 Amp output. Here's pics:
http://s92437987.onlinehome.us/ebayp...sc/rdc15-a.jpg
http://s92437987.onlinehome.us/ebayp...sc/rdc15-b.jpg
http://s92437987.onlinehome.us/ebayp...sc/rdc15-d.jpg
This pic, included for completeness, shows the V.O. side (which as I said, doesn't work - besides which the dials are fogged):
http://s92437987.onlinehome.us/ebayp...sc/rdc15-c.jpg