The Iron Man-3 4Wd chassis for the Arduino is now on sale on Amazon at a price of $237.99 + $9.99 shipping. The list price is $305.99, so you save an amount of $68.00 (22%).
The platform is designed to deal with uneven terrain and carry up to 2.2 Kg (5 lbs).
The chassis is made of steel to provide rigidity and durability. The motors feature metal gear and provide 220Rpm. Also, the platform comes with off-road tires that perform well on almost all surfaces.