Example sentences
zhè这ge个pián便yi宜duō多le了。
This is much cheaper.
yǒu有méi没yǒu有pián便yi宜diǎn点de的？
Anything cheaper?
About this word
便 means convenient and 宜 means suitable, so the pair reads as "convenient and fitting". The route to "cheap" runs through an older sense of advantageous, to your benefit: a price that suits the buyer is a good deal. That sense survives in 占便宜, to take advantage of someone. Keep the pronunciation straight, since the word is piányi with a light second syllable, and 宜 is the 宜 of 适宜 (suitable). The word is about price only, so it never means shoddy. For poor quality Chinese says 质量差.
The story behind the character
便
便 is 亻, a person, beside 更, to change. Xu Shen wrote 便, 安也。人有不便，更之: comfort, because when a person is uncomfortable, they change things. That is the root of 方便 and 顺便, things that go smoothly. 便宜 uses a second reading, pián, where the sense slid from a good deal to a low price.
宜
宜 is 宀, a roof, over 且, which in early writing is a stand for offerings, meat laid out on a table. Meat under a roof, set out properly, so the meaning became fitting, suitable. Xu Shen wrote 宜, 所安也: where you can be at ease. In 便宜, both characters say the arrangement suits you.