If you get a good seal and if the IEMs you use have good isolation, you'll hear able to hear all the music AS IF you were alone in a quiet room, even in a noisy plane or in a metro.
As for cost, I think you have no idea how procurement works.
Contrary to what you think, not all parts are made in China by the ton and using underpaid employees. Some of them are special orders or even small series with manual or semi-manual processes. The smaller the series, the higher the unit cost.
And concerning IEMs for audiophile, we're not talking mass production, unlike PC/Mac parts for example.
To cut part prices significantly you'd have to buy tens of thousend parts regularly, only the largest IEM manufacturers can hope to achieve that, and mainly for low-end models.
And to end it, maybe you skipped previous posts, but other than parts, final prices include R&D, functional costs, quality, maintenance, shipping, marketing, aftersale (...) and for each of these you have salaries, equipment etc etc.
Evaluating cost based only on raw materials or parts is just nonsense.
Profits are still there of course, and they're usually percentages, not fixed margins. After all, high-end products usually requires more efforts, and sell less, why wouldn't you gain more per unit sold?
