I would have thought a mambamax would be plenty for a 1/8 buggy/truggy really- run an external BEC or Rx pack & a little fan, should be plenty of power with something like an 11L feigao or similar. Heck, even the hvmaxx does brilliantly in something smaller/lighter than an emaxx, and there are loads of those on ebay all the time for about £80-90.
I'd steer clear of the ebay boat/plane escs, as the brake isnt proportional- on/off type only. There is this option though:
http://home.comcast.net/~truerc/esc/escNmotor.htm last one on the page.