The alternative shell looks like the following picture. You can find it cheap on e-bay if you search for 1:18 body shell. For matching bodies check the wheel base. For on-road bodies remember that this car needs a lot of suspension travel for off-road use. You could adapt it to on-road with shorter suspension but it would be perfect.
The new 1:16 4WD racing buggy from Hobby King looks even better. But then you'll also have to pay more. It's basically the same chassis of the other 1:16 off-road cars.
The platform, the wheelbase, suspension, electronics, etc is more than fine for that price. It's a small but oh so quick car. Arms have more than enough travel. I really like to beat this car so I found some weak spot. For now only a single part broke/got lost. The point where the rear gearbox connects to the wishbone was flexed too much causing the wishbone to get lost. I already received a new wishbone but the rear gearbox I will try to fix first.