Well you can get what are 'moneybox' machines I think in corner shops in London and they charge on average about �2.50 So I haven't been hit for a fiver yet. But �2.50 is still cheeky ;.(
I have never seen one charge over �1.50.
You get 2 chances to cancel if you dont want to continue. I personally do not mind them, they are safe and convenient, I have seen them in pubs and clubs which is handy.