Would like to know if there are any cheap power meters out in the marketplace and if they are worth the money.
2nd hand Powertap is your best bet. If you are patient you can pick on up for £400-£500
I can buy a lot of other nice kit for the price of a power meter, but if you are willing to just have it on the turbo, you could try using trainerroad.com with an ant+ device? Seems like a very good way of doing it on the cheap. You will need to check that you turbo is one of those with listed calibration for trainerroad.
Thanks to responders for information. Will look at both options.