I don't think there are any YHAs that charge any where as little as that.
That's not too bad all things considered. Dorm beds have not gone up so much, though it depends where you go but I remember it costing me £9 or £10 a night in 1993, so nearly 20 years later, it's gone up a fiver. The trouble is there are less dorm beds. Anyway, inspired by this thread I have planned a family week away in the Hebrides, not yet booked but soon will be. For the four of us a room is £80 to £70 a night. B&B equivalent would be £120ish a night and if I wanted dorm beds in the hostel (if available) I could save myself £20 a night. So say around £480 for 6 nights in our own room or £360 for dorms, as compared to a cottage for £700 in the same area. Camping would be £120ish, and the B&B £720 plus meals, so I guess it all depends what you are comparing it too.