Im training at Plusnet atm, and during the first week we were told that if a customer was to max out their 8mb line 24/7, it would cost the ISP £1500 a month.
that figures out at £0.60p per GB if Im figuring correctly.
Of course, it would require the person in question to find themselves something like 2500 terabytes to download, and a house which has its own exchange so they can actually get 8mb rather than "8"mb like the rest of us get.
TBH I think my 4MB real speed connection is quite fast enough, and my fair usage policy doesnt kick in unless I pass ~60GB/month. Perhaps Im just wierd/old fashioned, but thats more than I could use if I tried.