GKT says that it's roughly $1 per click. I believe that Google takes out 32% (correct me if I'm wrong) and the advertiser receives the remaining 68%. Yet I typically only get around .20 to .30.
I suppose I'm lucky in the fact that my adsense has a ridiculously high CTR of around 13% or it'd be making nothing.
Anyhow, what is your discrepancy between Google Keyword Adword Tool and what you actually receive per click?