For immediate funds:
I once raised over $1000 in two weeks doing the following: everyone has a jar or a cup somewhere where they drop the day's/week's change. No wants to roll the pennies. We had a few drop points for pennies and got a bank to agree to let us automatically roll them.

The school had 200 children. Their parents and their neighbors contributed. It was one of those fundraisers where everyone, even the unemployed, could participate.

International coordination presents a challenge but it is doable.

SINS