Youve got a ton of options if you want 4WD offroad.
The first thing that comes to mind is the good old T-Maxx. I think it would fall into your price rang pretty well.
Then theres other like the new HPI Savage, Ofna Dominator, Pirate, and Titan. Tamiya Terra Crusher. Comming soon is the Associated Monster GT.
If you don't want something quite as big as a monster truck, there is the HPI Nitro MT. It is about stadium truck size with 4WD.
Then there are the 1/8 scale 4WD buggies. There are so many it is too hard to list.
All these are great trucks, but if i were you, i would get the
T-Maxx. Its got the new 2.5 engine in it so its pretty darn fast. I also know its very durable and will take a very big beating. After all, it was designed for people like you who want to bash things around.