It will be quite expensive. Here is what you will need. Info gotten from Hobby-Lobby, this is the same equipment that was used to convert a 12foot Telemaster http://www.hobby-lobby.com/telemaster12.htm

PM533024 AXI 5330/24 Brushless Outrunner Motor ..... $ 209.90 http://www.hobby-lobby.com/brushless-axi5330.htm
These motors are extremely reliable IMO

JESAP90PW Jeti Advance PLUS 90 Amp Brushless Controller with Program Card ..... $ 182.00 http://www.hobby-lobby.com/jetiblue.htm

Four -- B3600N8 8 Cell 3600 mAh NiMH Packs @ $ 79.90 ea http://www.hobby-lobby.com/hydride.htm

Three -- SER003 Powerpole Connectors @ $ 3.00 ea

GR6412 Graupner Ultramat 12 Automatic Charger http://www.hobby-lobby.com/chargers.htm or similar ..... $ 99.90

PE20011E APC 20x11 Electric Flight Prop ..... $ 16.80

Approximate total around $837.20 plus shipping

You may be able to find cheaper components if you look around some.