贵 (guì) 'expensive' carries the shell radical 贝 (bèi), which marked words about money and value because cowrie shells were once used as currency. From a core sense of high in value the character extended to mean costly or expensive, and also honoured or noble, as in 贵姓 (your esteemed surname). The traditional form is 貴.

Origin

phono-semantic compound

Root

贝 (shell/money, semantic) with a phonetic upper element