Spend $16 and just buy the book.

http://www.amazon.com/Training-Racin...-2147483553-20

There is a wealth of knowledge here that will teach you how to train properly and help you decide if you are willing to do the hard work involved to warrant the purchase of a powermeter.

I love my Powertap and it has helped me improve dramatically in the last 4 years. My threshold power ouput has improved by about 30% (which is huge) and I am 50 years old. Anyone who thinks this power system doesn't work either hasn't tried it or didn't do it properly. Anyone who trains seriously just "by feel" likely hasn't reached their true potential (ie. providing the optimal stimulus to make muscles stronger over time isn't intuitive).

On the other hand, I go through stretches where it makes my cycling somewhat of a chore instead of a fun hobby and then I need to get away from it for awhile. You might read this book and decide not to buy one, in which case it was still $16 well spent. Just buy the book and start learning.