I shop weekly (get it delivered normally as an't get it all in the car with the kids too!)
There are 7 of us (two adults, 5 kids) so didn't do the poll thing but i spend £150 or under a week and that includes nappies, wipes (not for much longer!!), toiletries, cleaning products, fizzy drinks etc but not hubby's alcohol as i make him buy that himself lol.
I write a set menu on a sunday for the week ahead and try to use the things we have/only buy in what we need/will eat. Most breakfasts are eggs or cereal, most lunches are soups, or sandwiches and most dinner times are meat, veg and potato. Kids have snacks a couple of times a day too and there is always stuff in the cupboard for the youngest to munch on so his medical condition stays stable (has to be munching a lot during the day, mainly carbs)
We don't have takeaways etc but do always have either a roast or a bbq on a sunday!
I still think £150 a week is a lot though, 8 months ago i was only spending £120 for the same stuff but food etc has gone up lots!