(Puts on flame suit)
Scratch the Novarossi .28 7-port Turbo and the Clocked Argus .21 (A52) off of your list. A .28 is waaaay to much for a buggy and I know two argus sponsored guys that just jumped ship because the motors don't last.
Personally I really like my JL .21 Pro but you need the Hong Nor 2047 Pipe to go with it for it to really scream.
You could also get a Clocked Werks B6/2058 and probably still be near your budget.