I have an Associated rc8.2e with a Tekin motor/esc which i would rebuy if i was still looking for a 1/8 buggy. To date i have bashed the hell out of it and haven't really broken anything just had to order some pins which came undone because not enough loktite (my fault).

For that kind of money maybe you could try the HPI 1/8 trophy buggy which i believe is about 450 RTR then you could pick up 4 sky lipos for it. A few people run them around were i live and they look pretty good. Maybe someone else could help better because everything i would recommend in 1/8 buggies is going to go for more than the 600 you have planned by the time you are done with everything.
I think i paid about 850 for kit and esc/motor combo and servo. You would still need a remote on top of that. Im sure there are cheaper out there but i really liked the associated
<br type="_moz" />