This video about the church in Mizoram, India is a beautiful example of giving from what you have.  It's not about going without or huge sacrifices.  It's about giving everyday - in your home - with no one watching except your children.   

Whoever gives you a cup of water to drink because you belong to Christ will by no means lose his reward - Mark 9:41

Recommended reading:
Business as Mission:  The Power of Business in the Kingdom of God by Michael Baer