http://www.electricscooterparts.com has stuff too
Honestly the Castle HV110 is a great choice for brushless motors if you can do without the sensor harness. I have 5 hub motors coming to me so I can build up a few Ebikes, and I also have a gearbox in proto stage so that fast brushless motors can be used on Ebikes. A decent conversion with no batteries will run you around $500 in electronics, and using RC equipment is both cheaper and a LOT lighter. 1hp from a 7 pound hub motor plus a few pounds of controller, or 1hp from a 14 ounce motor and 5 ounce controller. Which sounds like a better choice?
Here are my current shenanigans
http://www.rc-monster.com/forum/showthread.php?t=9657