Google Adwords SUPER Tip #12...
EXPERIMENT WITH DIFFERENT BID PRICES AND CHECK CTR
Another quick way to test for better efficiency is to vary your bid price - and see how it impacts CTR and total number of clicks you get for your ad.
Some times it'll be better - or it may be worse. Either way, you win - because you know your pricing 'sweet spot'.
Turn Your Ordinary Business Into A Cash-Flow,