XBot

Mini Robotic exploration platform

System
Mini XPlus - Allwinner A10, 1.0 GHZ - $80
512 Megs of Ram
Wifi 

Cameras
1x Microsoft Lifecam HD - $50

Batteries
2x 3 cell 600mah NiMH - $16

Chassis
4x 6v Gear Motors - Sparkfun ROB-08912 - $48
4x Wheel - Sparkfun ROB-08899 - $28
1x Motor Controller - Pololu Qik 2s9v1 - $25

Misc 
1x Aluminum Sheet - $12
Tape, Wiring, Connectors, Switches, etc  $15

Total: $274

I hope to get the total price down with better part selection.

Source code
Video