Is there a program that helps you pay for travel costs if you volunteer your services in another country?

I'm becoming an RN and I would like to volunteer in impoverished countries to do mission trips, but most of them cost a lot of money. I know it's tax deductible, but we have to pay for it up front.
I have 3 small children and a husband, I'm thinking about us taking a month vacation or so.

Join the Peace Corps.

Peace Corps