Here's a fun idea (but this isn't really a must have by any means):
Take a smartphone with a USB port and WiFi and use that as the robot controller, most have at least one camera, some 2.
Use the USB port to hook up to the I/O devices through a custom module.
Don't bother with a router, don't bother with a PC.
Now the whole robot controller core is feather weight, has it's own power supply with battery, and is well the size of your phone.
All the radio bands you could want, when you don't want it, sell it off...people buy these things.
Hmm, is there an app for that
?