Typical cost of a short-haul flight

[Nicholas49]

Not sure how far I'll get with this, but could some financially-savvy person tell me what the approximate cost of operating a fully-laden two flight using a B737 or A320 aircraft (for the sake or argument)?

I do realise there are any number of variables, but I would be interested to have a ball-park figure for the amount it costs an airline to carry out such an operation.

Thanks