AdWords has a recommended budget for your campaigns. Should you spend more, less, or follow their advice?
I found that I really get the best results when I set my daily budget to 150% of their recommendation. (So, if they recommend $200, then I set it to $300).
This get’s me not only more clicks, but also sometimes can lower the CPC.
One possible reason for that might be that some competitors run out of budget at some point – at which there is less competition for that keyword, thus the ad price drops temporarily. But that’s just a guess 
