I've taken my first step into a larger world. While I am still completely ignorant of all things electronic, but my Futaba 7 channel transmitter and receiver are the first things I bought to make R2 run. The transmitter has seven channels, which is much more than I will ever need. Honestly, you could probably get away with four if you just want the droid to drive and dome to move. Many builders are using higher-end 9 channel units, but I don't plan to add too many bells and whistles, so I couldn't justify spending considerably more money on two unneeded channels.
I purchased mine from www.towerhobbies.com. I got the ground frequency model so I don't bomb any nearby airplanes. I don't want the FCC to come after me! It came with two servos, but I don't know where I'll use them yet. Maybe a door or fire extinguisher, but that is a long way off.