So LVMH started to watch its customers more closely
Speaking on a conference call earlier last year, Jean-Jacques Guiony, chief financial officer at LVMH, said: "We've placed strict retail restrictions for the amount of products that people can buy.
"But, when you see someone in a store, you don't know whether they are buying handbags for themselves or to sell them on to the market in China. We are trying to make sure we are not competing with our own products in the China market, but our actions are not entirely bullet-proof."
Grey market
Other companies have found it easier to try to equalise prices. The fashion house Chanel raised its European prices by 20% and cut them in China, directly competing with the daigou agents and successfully eroding their profit margins.
This kind of grey market happens everywhere.
A supermarket might halve the price of a box of chocolates in a sale and sell them all to a single customer, only to see them turn up in the corner store down the road, undercutting their recommended retail price, a fortnight later.