It's cheaper to buy in bulk.

　　大批購買(mǎi)便宜些。

　　The company seems to be doing so well that I would like to buy in.

　　這家公司看起來(lái)生意興隆，我愿意入股。

　　He will buy in as a partner.

　　他將入股成為股東。

　　It is usually economical to buy washing powder in large quantities.

　　大量購買(mǎi)洗衣粉通常要省錢(qián)些。

　　Many farmers buy in ewes in autumn.

　　許多牧場(chǎng)主在秋天大批買(mǎi)進(jìn)母羊。