I fancy that cheap HRM/power meter estimator thingmy, wallet says no after On One Fatty purchase, is there anything cheaper to display my wattage than the Cateye Stealth 50 @ £100?

Bontrager Node 1.1 for £40? http://www.evanscycles.com/products/bontrager/node-11-computer-ec036090
It should work with a power meter. Note it doesn’t include any speed/cadence sensors, you need to buy those separately if you want to see that.

Estimator thingmy?

Powercal?

Head unit: used Garmin 500 or Powertap Joule.
Meter: Powercal HR/Power

The Powercal has its detractors, but I’m a fan. On 10 or 30 second averaging, it is a good estimator of effort that correlates well with my Stages.

Phone and a bluetooth HRM?

PowerCal should work fine with that bontrager one, looks a bit of a bargain.

What TiRed said… the PowerCal won’t tell you how much power you’re really making but for a 30s average it’s ok. Most useful for getting a pretty close NP and TSS for a ride. Lots of cheaper direct power meters on the way into the market soon too.