I've raised £50 to help Syros Cats neuter stray cats

Some of you may remember that J-P and I spent some time volunteering on Syros (a Greek island next to Mykonos) in 2009. For the last month of our stay, we lived next to the sea with little to do but play with the local stray cats, of which there were many. I hoped then that I would return one day to arrange for many of them to be neutered - the local population is fairly well fed by the locals but uncontrolled and therefore growing quickly.
A couple of years ago, Google showed me that someone had beaten me to it (which made me both happy and a little sad that I'm not there to help). Syros Cats is a not-for-profit organisation that helps sick, injured and abandoned cats on the island. They fundraise to help cover the costs of feeding, neutering, medication and veterinary costs and all money raised is spent directly on the cats.
I'm running another marathon this year and I've signed up for one for next year too. I know some of you would like to show your support by sponsoring me so I'd like to target this tiny charity where whatever amount we can raise will really mean something. I'm not running 'for' Syros Cats, I run for me, but if this can help them too then it's a bonus.
It costs Syros Cats anything up to €50 to neuter a cat (it depends on what arrangements they can make with the local authority and other factors). They also want to subsidise neutering costs for locals so that they can be part of the solution. Neutering is beneficial to individuals cats and to the community. Unspayed females, especially those that are fed regularly, can easily produce up twelve kittens each year. Unsterilised male cats pass on Feline AIDS and Leukemia and exhibit aggressive behaviour.
Between us, can we sterilise one cat? Two? Twenty? 26.2?
Thank you for whatever you choose to give.