The 1/8 Scale buggies are some of the most durable r/c's out there and should kick a 4x4 slash's but on the track. They are fast, handle extremely well, and are extremely tough. Just a great r/c all around. You can pick up the Ofna LX-1E for $200, and then with the electronics and batteries it should still be at or under $500.
http://www3.towerhobbies.com/cgi-bin...&I=LXYCA8&P=ML
Just another option. There are many good r/c's now though.
Eric