EASY (IER) KANJI - JLPT 3 KYUU

A lot of money words also have shell kai [] as part of the kanji. A long time ago shells were used as money.

1) bai, 2) kau - buy

買い物 kai mono - something to buy, shopping
売買 bai bai - selling & buying, trade
買主 kai nushi - the buyer, purchaser