Are you looking for an affordable robot platform? Say no more. You can make one your self from an affordable toy. I believe it is called a “tumbling car”.
You just need 2 of them. They cost at around 50php each. The total will depend on how you are going to attach them together. So probably at around 120php, more or less.
The mechanism of the toy is pretty simple. The built-in battery box is just connected to the motor in series via a switch. The motor drives a gearbox that drives the 4 wheels which makes the toy a 4WD one.
As I said that we need 2 of them, this is because so that we could make it turn right or left, not just forward or backward.
Just shorten the shafts of the wheels(It is marked on the image above). And be creative on how to attach the 2 halves together. Make sure the way you attach them is sturdy. Do not forget to wire the battery boxes together. There, free battery box too.
Enjoy adding your own electronic circuit.