I am using Google Ad network for advertising my sites. I had given around $0.50 to $0.80 previously for single clicks. But last week I paid $5 for just one click. I know that PPC's can vary sometimes but this much? What's your say?
PPC rates is dependent upon the demographics and nature of the click. You must have been clicked from some front tier country that's why you are paying much. If you are using Google then you may have plenty of options where you can set your CPC rates and also the countries your ads will be shown.