I've been teaching CompuTrainer indoor cycling classes for 20 weeks now. I've watched my athletes take 30 minute FTP tests from 200 to 260, 250 to 315, 221 (in aerobars) to 245; all in one winter! Many of those riders don't have a power meter to use in the summer.
Here's the deal... if you made that kind of progress indoors, why, why would you not want to do that year round? Imagine where you could take your athletics?
So... I became an SRM dealer. Top of the line power meters offered right here. I pass along my discount to you (along with a one time $25 fee if you are not a coaching client). I could get you Polar power meters - I have one. It works great. I could get you a Power Tap - I have used one. They are great too. I'm lovin' the SRM. This thing is the bees knees.
If you're interested in a power meter, give me a call. Take a look at what SRM has to offer; and lastly, I take more than a quarter off of what you see here.