I would not stress so much about the amount, just work on lowering it little by little. Shoot for 600 this month then 500 and so on, until you are as low as you want to go. Make menus and shop from them only. Eat out less and take lunches to work. Do it little by little so that you don't jump off the boat. It can be done for 50 a person a month, but you best be a good cook. Here are some web sites that have some helpful ideas and recipies.
http://www.savingdinner.com/
http://snider.mardox.com/
www.hillbillyhousewife.com
These sites are great and will help you get started...remember little by little will get it done