I can't really help you with costs or firm numbers, because I don't currently commute
however I thought I'd toss in my two cents about my location criteria while job-searching....
We're in Redcar now, so about 15-20 minutes east of Middlesbrough, and in order to get to any of the large towns or cities around here, you pretty much have to drive or take the train to M'bro first. So that's 15-20 minutes (around 7-9 miles) by car, or half an hour by train, to start. A job in Redcar (or the surrounding area - Guisborough, Marske, Saltburn, etc.) would be ideal, or in M'bro; less ideal, but still quite close (at least by American standards) is Stockton, Hartlepool, or Darlington. Stockton would mean around a half-hour drive; the others would be more like 45 minutes. None of these places are teeming with potential professional positions, though, and so I've necessarily expanded to Durham (about a 45 to 60 minutes drive west-ish, depending on route and traffic), Sunderland/Gateshead (about an hour's drive north), and York (about an hour's drive south). At a stretch, I'd consider commuting to Newcastle or Leeds, but it'd have to be a full-time, professional position that really made the commute worthwhile. (As of yet, the absolute best position I've found is in Manchester - just a weeeee bit too far away to be feasible.
)
Being in Sheffield is, I would imagine, like when I lived in Boston - you're both blessed and cursed. There are quite a few more jobs there than there are around here, but you're competing with all those grads!