Firstly, it is worth noting that SkyScanner.net is merely a price comparison site and not one that actually sells you flights. The idea of the site is to save you the legwork and to search lots of airlines sites using the dates, times, airlines, airports etc. that you provide. As for NetFlights.com, I have only once or two found that some of their too-good-to-be-true fares have sold out, but never ever have I come across a price hike of 50-100% on the next most suitable flight. £20 or £30 maybe, but I think you are exaggerating!
djtdjt, I laughed out loud when I read your reply. You are joking, right? To say that easyJet do not "pile on extra charges" is just ridiculous. I have just gone through the booking process for a flight from Gatwick to Barcelona - although with no intention of booking a flight. The outbound fare is £30.99 and the return is £19.88. By default, the airline has automatically added 'Speedy Boarding' to my booking at a cost of £14.00 for the two flights, they want £16.00 from me if I have checked baggage and they have assumed that I wanted their travel insurance at £8.99. Frankly, at almost £80.00 for this return flight, I don't think that represents good value for money. The fare that was shown to me originally was somewhat appealing but the extra charges have really hiked the price up! And if that isn't insulting enough, easyJet want even more money out of me in order to pay for this flight unless I am one of the very few people who uses a Visa Electron card.