I think the phrase 'low-cost' airlines has moved on a bit since five years ago where Ryanair et al would charge 1p for the flight and the only extra would be skiing equipment or a credit card fee.
Now that they have so many extra charges, the cost is only 'low-cost' if you chose to avoid them and BA have been proving that on their website.
I think it is always best to search around for the best fares including ALL costs.