Take the family on periodic “spending fasts.”
As an exercise, go a day, a weekend or a week without spending any money. Make due with what you have.
Encourage participation. Tie in spending fasts with holidays, lent or in support of a cause.
Check out the Jesuit Volunteer Corp. A short but deeply meaningful immersion into service, faith in action, selflessness and living on a lot less than you think you need.