your best uption would be to try and use an onroad 1/8 and convert that to brushless ...... sick speeds and may even match the 1/10 for excelleration.
I have 2x of the prp's that i'm gonna convert myself....
there wy less expensive then the megens, kyosho,and serpent, but performance is the same :-)
http://www.powerracingrc.com/images/xr8/xr8main.jpg