... If you're patient... if you live in (or can fly from) the UK
Jack's Flight Club might be one of the worst kept secrets nowadays, but I don't think that takes away the value of the service!
Essentially what the service (or Jack you could say?) does is find either mistake or underpriced flight tickets. Some of the deals I have seen include Tokyo for £250 (saving around £400), and business class to Los Angeles for less than £500!
Sadly I haven't had the opportunity to use one yet, but I hope to soon!
The caveat then for anyone outside of the UK is that the flights focus on airports within England and Scotland, meaning that if you want to take advantage of the deals you would have to spend on a flight here first, which may actually take the discount away
Have you heard of any similar businesses like this? I would love to know if there are any more!