I suggets you check it out on the internet and if you are on a fleet that flies to the states have it done there. It will cost you less than half of what these robbers in HK will charge you. HK $ 1500 for an earplug is nuts. Even if it comes with accoustic filters.
Also suggest you go to a good music store and get a pair that musicians use - they also come with the interchangeable acoustic filters - but are obviously not customised for your ear - however they are US 15 $ and will give you an idea of whether its worthwhile to go and have a custom pair made.