Powertap GS Hub Power Meter - $299 + FS (reg. $599)
Note that this is for the hub only...you will still need to build a wheel around it or get your wheel re-spoked. Still, given the accuracy and durability of this hub (it has DT Swiss internals), it is still cheaper than most other power meter options.
There are pros and cons for any type of power meter, but this is a great hub from a very respected company.
Here are the specs from Powertap:
- PowerTap GS straight pull hub shell
- 24-spoke rear
- Weight: 320g
- DT Swiss bearings
- Compatibility: Shimano/SRAM or Campagnolo
- Powermeter accuracy of +/- 1.5%
- Field-serviceable electronics
- ANT+ or Bluetooth Smart
- Battery: CR 2032
- 9, 10, 11 speed compatible