Buying items by the box; purchasing goods in bulk in their box packaging (e.g., drinks, snacks).
パーティー用にジュースを箱買いした。
I bought a box of juices for the party.
箱買いすると1本あたりの値段が安くなることが多い。
When you buy by the box, the price per unit often becomes cheaper.
最近は消耗品を箱買いしてまとめて管理している。
Lately I've been buying consumables by the box and managing them together.