This is a preliminary list of components for the balancing and power electronics and where to find them.

Arduino Uno

http://store.arduino.cc/index.php?main_page=index&cPath=11

Arduino Mega

http://store.arduino.cc/index.php?main_page=index&cPath=11

OSMC Motor controller

http://www.robotmarketplace.com/products/0-OSMC.html

XBEE wireless receiver

http://www.adafruit.com/products/128

BATTERY PACK:

Cheap (relatively) e-bike LiFePO4 20AmpHour 24 volt pack from Hong Kong:

Here is a similar one on ebay:

http://www.ebay.com/itm/24V-20AH-LiFePo4-Battery-Electric-Bicycle-Scooter-E-Bike-Rechargeable-Free-ship/181426354090?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D22425%26meid%3D7497033859865692253%26pid%3D100005%26prg%3D9723%26rk%3D1%26rkt%3D5%26sd%3D371075633814%26