No, but that price you've given would be the exception by a long shot, not the norm. In the last 18 months I've flown London Dublin for less than US$28, London Prague for US$45, and Athens Madrid for US$88. Anyone with experience flying in Europe knows that number you give is simply ridiculous.

The only thing I'm left wondering is why you'd suggest 400 for London Belfast on a LCC might be anything like normal? Looking at Google Flights for London Belfast just now (scroll down and select 'graph"), the average flying anytime from tomorrow through to the end of Feb is ~NZ$69 return. Even flying in the next ~36 hours only puts it up to a max of ~NZ$250 return.