Cheapest place to get the motor is direct from the disributor- castle creations, though its built to order so will take 4-8 weeks to arrive:
http://www.castlecreations.com/produ...motors/nm.html
As for the escs, there isnt a huge number to choose from:
http://www.castlecreations.com/produ...a_monster.html
or the Schulze line up- bearing in mind they cost about twice as much for the basic models, and it only gets worse:
http://www.schulze-elektronik-gmbh.de/prs21_e.htm (18.97 onwards)