It's cheaper to buy in bulk.

大批购买便宜些。

It's illegal to get into a formal agreement with investors that they'll buy in the aftermarket.

与投资人达成正式协议允许其在后市买入是非法的。

What can we buy in the grocery store?

我们可以在商店买什么呢？

Should we even buy in the first place?

实际上我们应该在第一个地方买吗？

They always buy in large quantities.

他们总是大量购买。