noun
item in excellent condition; used item in great shape
Commonly used in online auctions and second-hand shops to describe a pre-owned item that is nearly like new, with minimal signs of use.
このゲームソフトは極美品です。
This game software is in excellent condition.
極美品のバッグを格安で手に入れた。
I got a bag in great condition at a bargain price.
新品 is a brand-new, unused item, whereas 極美品 is a used item that looks almost new.
Compound of 極 (ごく, 'extremely') + 美品 (びひん, 'item in good condition'). The term is widely used in second-hand market contexts.