FYI the production cost of that bag is estimated to be $800... so a mark up of 1250%.
A true economist would say the critics are hypocrites given the cup of coffee or bottled water every other passenger carry onboard carry a mark up of 1500 and 2000 percent respectively. They are also consumed within minutes and hold zero resale value.
Sorry about your bag, no doubt it was important to you and you worked very hard to buy it. I hope you are able to restore it to it's previous condition.
I would be curios to know where you got those figures on water from? Given the
cost of a plastic bottle is around 2.5p and that as I recall you can but 0.75L bottles of water at WHSmith in T5 for £1.50 that seems to exclude the possibility of such high mark ups.
The way I look at it is that the OP is creating far more jobs (and better paying jobs) by buying a £8000 bag than a cheaper brand. Really none of our business what people choose to spend their money on (as long as it's legal).