Was trying to find a minimalist way to mount a driver on my TC3. In total this solution cost less than $10 USD.
$4.40 (1) Tamiya part Z58124 (0225001) - Driver head/shoulders (http://www3.towerhobbies.com/cgi-bin...?&I=LXLDW5&P=7
$4.00 (1) Traxxas #4919 Servo mounts (2 in package)
N/A (1) Stock TC3 battery strap
I drilled a hole in the side of the battery strap and the base of the servo mount and secured with 1 screw. The entire setup is about 10-15 grams of weight.