Moo:

I use a Vantec electronic speed controller (ESC) for my RC Armory 1/8 King Tiger. Try,

[link]http://www.vantec.com/products.htm[/link]

They're not cheap (RDFR22 will be around $280). But, these are industrial ESCs and they're reliable.

Briz mentions robotmarketplace and the Scorpion XL -- this may be just fine for what you need, and cheaper, so you might want to take a serious look at that one too. (I'm not familiar with the product so I don't have an opinion).

Either way, you should make sure you use a controller that is voltage-compatible with your motors or you might fry one or the other (ESC or motors). It's best to talk with the ESC supplier, tell them what you want to do, and ask for advice on which ESC will fit best.

Cheers...