looking at the shot you linked to this could be achieved by parking under a streetlight and using the on-camera flash with trial & error on manual settings...
but
if you want a cheap solution for wireless trigger get the Yongnuo ones off ebay
eBay - The UK's Online Marketplace
I bought from this 18 months ago and have used on various jobs - for £35 it's great value and well made
bear in mind they will not sync above 1/180s so not brilliant for action shots
but then again the flash freezes alot of the action anyway - I have not found that an issue.
the trigger will connect to virtually any flash that uses standard voltage trigering
make sure the flash you get has manually adjustable power output
learn how to use the camera in full manual and how aperture / shuter speed works when using flash
[aperture varies total amonunt of light getting into the camera - shuterspeed just the ambient light - flash power the ammount of flash light]
then it's a lot of trial and error... but simple really once you crack it
search for 'strobist' on flickr or net for ideas