I scrounge the classifieds here, on
www.slowtwitch.com, and I look on Ebay. These came from a guy on Slowtwitch.
That's the cool thing about 650 wheels; lots of people are moving away from them and you can pick up deals if you are patient. I just bought a rear 650c wheel with a Powertap hub for this bike for $150.
I need another install kit and then I'll be able to use my PT Pro on both the road bike and the tri bike.