You've taken an important first step if both you and your ex agree that the two of you are spending too much on the kids. Kids really need time with their parents more than they need things. Start doing things with the kids that don't cost a lot of money. Museums, picnics and hikes all come to mind. So does volunteering as a family at a local shelter or food bank. A resource we recommend to parents for ideas for family experiences and family outings is Kidsoffthecouch.com
, which offers weekly suggestions on how to pair watching a rented movie with family outings and discussions.