It costs usually $50 or less for us to eat each week. We go grocery shopping maybe once a month and spend about $80 or so, then we just pick up a couple of things here and there after work when we need it.
How often we eat out depends on what is going on that week. Last week we ate out 2 or 3 times, then this week we ate out once so far. If we're going to be away from home for the day we usually eat lunch out. If we're just hanging around at home, we cook.