This is way too much of travel 101, meaning everything is surface. It's annoying that prices in paris are compared with that of taiwan. There is no comparison, you are in Paris.
很高興你喜歡巴黎,看到你們經過哪些很日常很熟悉的地方還蠻奇妙的。le samaritaine樓下的化妝品護膚品打折的時候也很便宜,出去黑五,打折季來應該是最便宜的,巴黎春天百貨好像還有遊客全場5%的遊客折扣,maison kitsuné, AMI 這種其實巴黎會有特賣,70歐一件sweat之類的,不過需要碰運氣。