The Centurion Club was set up by PDG Peter Walsh. It asks that each Rotarian donate $100(aud) to the Foundation each year, in line with EREY (EveryRotarian Every Year) which runs in most countries.
We already give $50 to Foundation as part of our fees. You should receive a tax receipt for that soon, if it hasn't already arrived.
Therefore our Centurion contribution would be an extra $50.
I need to stress this Centurion Club is totally voluntary
and the details are kept confidential. 
Secondly I just want to talk about Paul Harris Fellow awards.
Originally, the PHF was recognition of a donation of $1000us, given to say thank you. At the time $1000 was a considerable amount, more akin to $10000 in todays terms.
We in Australia decided that the Club could award PHF recognition, and that they would seek out outstanding individuals in the club or community who deserved recognition. It became an award for great things, and that tradition has continued. So while in America and most other places around the world the award hasn't changed, here we do it differently and I think our system is much much better.
Over time our individual donations to the Foundation do add up to $1000us and the Foundation will let us know. We then as individuals can pass these on to the Club to award, or even select someone to award it too. Equally we can accept the award ourselves. It is up to us.
The foundation is our own Charity, and we rotarians can do enormous good by accessing funds from it. but that is the subject for another article.