Here, there's a group of up to about 10 of us who smoke together regularly. Everyone buys their own stuff and we just pool it together for whoever wants some. So it ends up being about 200 quid a week, more if there's guys who deal hanging round, obviously. It'll end up being around 2 or 3 ounces during the course of the week.
Personally I spend about 20 or 30 quid on my own, more if I'm buying for my gf or her brother and they can't pay me til weekend.