I have a daily commute of 36 miles each way, and I spend around £250 a month on fuel which includes social and domestic journeys as well as the daily commute.
That's with a 1.8TDCi Focus doing around 60Mpg on the commute, as my entire commute is country B roads, almost the whole journey is spent sat at 60 apart from a few small villages and 2 junctions. Obviously if your commute involved a fair amount of city driving then that would end up costing more in fuel, and time.
I'd echo what others have said regarding extra money require to break even, unless it's a job you really want, it may not be worth the commute. Especially given you don't run a car already.