I have a handful of Power supplies...
The old Pyrmaid 30amp boat anchor used to be my choice, but now I do convert old PC supplies.

I put an in-line fuse holder & 15amp automotive fuse, & some female banana jacks on an old Dell 400+ watt. I have had no problem pulling 10 amps to break in mod motors on the ICE charger & the supply is reasonably sized.

Newegg has a hand full of "Single 12+ Rail" supplies for a reasonable price
You can definitely go bigger & "Dual Rail", but I don't know if there are any problems crossing rails.

Here are a few based on ratings...
Junker name brand:
$30 - 15amp
http://www.newegg.com/Product/Produc...82E16817182006

$25 - 20amp
http://www.newegg.com/Product/Produc...82E16817255040

$55 - 35amp
http://www.newegg.com/Product/Produc...82E16817182010

Good name brand:
$40 (but has rebate) - 18amp
http://www.newegg.com/Product/Produc...82E16817153023

$60 - 35amp
http://www.newegg.com/Product/Produc...82E16817148008


And the one I want... (ooohh! now on rebate)
$60 - 34amp
http://www.newegg.com/Product/Produc...82E16817148005