買えばいい

should buy

→ 買う
phrase Uncommon #16,671
should buy The ~ばいい pattern expresses advice or indicates that doing something is sufficient; depending on context, 買えばいい can also mean “just buy it.”
JA: 気に入ったなら、買えばいいよ。
EN: If you like it, you should buy it.

鉛筆あと何本買えばいい

How many more pencils do I need to buy?

フライピザを両方買えばいい

You could just buy both fries and pizza.

— 恋する惑星 (1994)

サラダフライ両方買えばいい

You should buy both the salad and the fries.

— 恋する惑星 (1994)

レコードでも買えばいい

You could always buy the record.

— キャッチ・ミー・イフ・ユー・キャン (2002)

どこで切符を買えばいいのか教えてくれませんか

Could you tell me where I can buy a ticket?

彼の誕生日何を買えばいいのかわからない

I don’t know what to buy him for his birthday.