false economy
noun [ C usually singular ] uk/ˌfɒls ɪˈkɒn.ə.mi/ us/ˌfɑːls ɪˈkɑː.nə.mi/
假实惠
an action that saves money at the beginning but, over a longer period of time, results in more money being wasted than being saved
Buying cheap household appliances is a false economy - they're twice as likely to break down. 买廉价的大件家用电器只是表面实惠——它们出故障的几率高了一倍。