I have a used PowerTap Pro SL system up for sale. It is a 32 hole Campagnolo compatible hub laced into
a Mavic Open Pro clincher rim using DT spokes. The rim and the spokes are black, to match the cool carbon fiber hub shell.
This was my training wheel and it is in fine shape. It probably has between four to five thousand miles on it.
The wheel comes with the handlebar mount, hub sensor, cadence sensor, computer download cradle, computer,
manual, CDROM and nifty carrying case you will probably never use for the computer and HR strap. I will also
throw in a new Polar HR strap and the original CycleOps one is "well used". You can use any non-coded strap
with the computer.
Don't let the Campagnolo cassette body scare you. You can buy a Shimano one from CycleOps for 59.99 and
swap it out. I originally had a Shimano body on the wheel, but swapped out to Campy and sold the Shimano one.
It probably would have helped to keep it.
Asking price: $1000.00
If you want to train and race with power, I also have a Zipp 404, 28 hole clincher laced with Sapim X-Ray spokes into a PowerTap SL hub. I raced this wheel about four times and it is in perfect shape. It was built by Richard Sawiris at wheelbuilder.com. It is the new Zipp 505 rim with the aero dimples and makes a neat noise when you go really fast.
I'll throw in a set of aero covers also made by Richard so you can use the wheel as a pseudo-disc during a TT effort. The covers are actually pretty good. You can see them here: http://www.wheelbuilder.com/ 
Asking price: $1150.00
Feel free to ping me with any questions. Thanks!
Gene Z. Ragan