ㄌㄨㄛˋluòㄧㄤˊyángˇzhǐㄍㄨㄟˋguì

  1. 左思三都賦時人相傳使洛陽上漲昂貴晉書··文苑·左思》。比喻著作風行一時流傳·》:寫字洛陽紙貴名震一時江湖。」

lit. paper has become expensive in Luoyang (because everyone is making a copy of a popular story)​ (idiom)​, fig. (of a product)​ to sell like hotcakes
(expr. idiom.)​ (litt.)​ le papier coûte cher à Luoyang, best-seller