There's a collection of infos about various torquesensors in the german Pedelecforum wiki:
www.pedelecforum.de
You can use google translate.
My suggestion is the Phoebe Liu Shop at aliexpress:
From my experience, the problem is not the sensor itself, but the controller, that can't deal with the sensors signals, if you don't want to have something ugly like the CA on your bike (sorry Justin
)
Therefore I started to write my own firmware for my controllers
regards
stancecoke