I'd say the same, go for it - work it out as an hourly rate and you get the extra legroom, better seats etc for £6 more per hour. Or if the £150 is for both ways, £3 per hour. We can all manage a four hour flight to Dalaman with pretty poor legroom etc., but it's amazing how much harder it becomes on longer flights. I used to travel business class to Dubai (which is around 7 hours) but one time the only way was economy with BA (the shame of it I know, I know!) and I was shocked by how cramped it was down the back! Also how difficult and long it made the 7 hour flight. I can't imagine how people doing long haul to Australia could survive economy for 23 hours or whatever it is. Your son won't be flying to Australia too many times I imagine so I'd say the £150 is well spent.
I wasn't paying for the flights by the way, it's amazing how much easier I deal with cramped flights when I have to pay for them myself
