Grocery shopping totals for week 1

I went grocery shopping yesterday afternoon and my actual food costs on the list totaled about $107 at Wal-Mart. My goal is to average around $100/week on my food budget. The only exception to this rule is when I go Costco shopping and stock up on meats and other essentials. Now, I just need to find a way to make it so I can go grocery shopping every two weeks because I spent almost 2 hours at the store with my 3 year old and 8 month old and by the end of the trip I was exhausted and lost all patience. Please tell me that all you other mommies get this way too! I have found that putting a quarter in the candy machine at the entrance helps my 3 year old stay on track, but seriously, im not into bribing my kids all the time to behave and 2 hours is an exceptionally long time to ask a child to just walk around the store with mommy and not play with all the fun stuff in the aisles. If any of you have a grand idea on occupying children's active minds in the store please share!