吃小亏占大便宜

throw a sprat to catch a mackerel

chī xiǎo kuī zhàn dà biàn yí ㄔ ㄒㄧㄠˇ ㄎㄨㄟ ㄓㄢˋ ㄉㄚˋ ㄅㄧㄢˋ ㄧˊ