Sorrows of the Millionaire
by George Bernard Shaw
In the advertisements of the manufacturers of the country, I find that everything is produced for the million and nothing for the millionaire．Children，boys，youths，“gems”，ladies，artisans，professional men，even peers，and kings，are catered for; but the millionaire’s custom is evidently not worth having; there are too few of him．Whilst the poorest have their Rag Fair，a duly organized and busy market in Houndsditch，where you can buy a book for a penny，you may search the world in vain for the market where the 50￡boot，the special dear line of hats at forty guineas，the cloth of gold bicycling suit，and the Cleopatra claret，four pearls to the bottle，can be purchased wholesale．
What's the meaning of the underlined part?
I presume that this is a case where pearls (who are inherently quite valuable) are used as a currency to pay for the bottle of Claret (red wine). So, it would just be another way of demonstrating that this particular bottle of wine is expensive.