idk thats a hrad question to answer. like what are you planning to do to the roller? just buy stock traxxas parts or get good quality servos an all that other good stuff. If i had that money i would wait for the 4x4 slash to come out with.

but if your just looking to make your own personal slash do some research on your own make it your project. find out what the correct servos you can use, different tires that can go on, and paint up a sweet body for it too. do your thing man