It's cheaper to buy in bulk.
大批購買便宜些。
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.
大量購買洗衣粉通常要省錢些。
Many farmers buy in ewes in autumn.
許多牧場主在秋天大批買進母羊。