well looking at it, you've got the esc and motor there, so would guess that pinion and spur gears are there.
In which case you'd be looking at a transmitter and receiver
I got this one off the bay, tis good and works well
http://cgi.ebay.co.uk/FS-GT2-2-4G-2C...item255c21c6f8
from china, so far all stuff i've ordered from HK has come within two weeks
and a lipo and charger to finish - always 2nd hand of each on the bay.
So cost wise I would guestimate somewhere in the region of £60+ 'ish?