Cage kits? You mean a full chassis? Do you want a tube buggy or modifying a body on frame vehicle? I am assuming you mean a production chassis. I would say that come down to what is your time worth? What kind of timeline are you wanting to have it RTR? Being new to the sport I will assume you will have a decent learning curve. So if you build your chassis from the ground up you will probably have some growing pains, re work and stuff when your done you wish you would have done different. With the production chassis most the guess work is done and you build the parts that fit your application. On the flip side building your chassis you can make it exactly how you want it.