for sport driving electric vehicles (read: bashing), a decent AM is all you really need. if you into club racing, then a sport FM radio is a definite must.
for nitro i like recommending all FM. reason being is it seems a lot more could go wrong in a nitro vehicle than electric that would cause interference within the vehicle itself to make you have a runaway.
as far as models go, any reputable radio company is fine: futaba, airtronics/sanwa, JR, and KO propo are all good names in the industry. they all make decent sport FM systems that should fit your budget. one thing is you may want to consider using the traditional crystal systems over the new synthesized systems. although convenient, i've heard of several drivers complaining about runaways, etc.
personally i like the ergonomics of futaba and airtronics/sanwa radios, but my personal radio right now is the Mars R. I love this thing as its compact and not very heavy. My previous radio is an M8 and it had a nice grip but was still a little top heavy even with all the batteries installed.