The rents are so high , that some people working in HK travel every day to and from Shenzhen where they live coz still works out cheaper incl. travel costs and time spend on the road ( subway ) .
Having a shop is much more pressure , so if sell items which are not like bottle of water or cigarettes type stuff ( frequently selling stuff ) , you need to put some serious margin to pay the rent.
But also as already mentioned here , every item ( in this case tea ) has it's customer despite the price. There are many selling and buying concepts give you a reasons why buy tea from vendor A and not from vendor B.
I believe there is no ultimate true in this ( what is better / fair price=value=quality ) formula as individual variables in this equation are speculable and individually perceptionable.
Somebody loves HK storage and somebody can't stand the taste.
Somebody can't taste difference from Guangzhou storage and somebody would fight to the last breath to convince everybody around that the difference is significant, as much as justified price difference ( in most cases the vendor or enthusiastic HK tea lover would do so. General tea drinker doesn't give fiddlers much about it ) .
I believe every buyer can justify their purchases.
