Concert merchandise lines move fast. You do not need perfect Korean, but a few short phrases can make sizes, quantities, payment, and pickup much easier.

Core phrases

Korean Meaning When to use it
이거 하나 주세요. One of this, please. Point to the item while saying it.
두 개 주세요. Two, please. Change the number as needed.
품절이에요? Is it sold out? Use when an item is no longer displayed.
카드 돼요? Can I pay by card? Useful at smaller pop-ups or cafe events.
사이즈 있어요? Do you have sizes? Use for clothing or wearable merch.

Small etiquette points

Pronunciation tip: You can survive with short phrases and pointing. Clear, polite, and quick is better than trying to explain too much in a crowded line.