I have learned that spending quite some time on searching for a the best fare for a trip can be quite rewarding. It isn't uncommon that I save 1000 Euro on a trip, simply by going through various resources. Still I often regret not having waited a bit longer in booking, because I notice an even cheaper fare. Then again it is also not uncommon that I waited too long.
It would be so nice if you can know the rock bottom (real) price of a given route. I say "real" because I know that airlines sometimes have 1-10 Euro stunt prices airlines, but that is like winning the lottery since they are so hard to secure. So far I only managed once to buy a return trip for 1 Euro.
So I am not talking about the stunt prices airlines use for marketing purposes.
This question is inspired by a Dutch documentary where a group of journalists investigated what it costs the airlines to fly between Amsterdam and London. If I remember correctly it was on average 60 Euro per seat. So I would consider 60 Euro a threshold price for a trip from Amsterdam to London. Anything below 60 euro's becomes a bargain.