Cost
Price
noun
When you buy something, you basically substitute it with money. That substitute money is the cost or price of the thing you're paying for.
There are a lot of money-related synonyms in Japanese, but keep in mind this one refers to the money you pay to get some stuff in return (usually goods), not to an expense, price, or value. It's "substitute money" after all!
This is a jukugo word, which means it uses on'yomi readings for both of the kanji. You already know those, so you should be good to go!
本の代金はカードではらいます。
I would like to pay for the books by card.
マッサージ代金は五十ドルです。
The massage costs 50 dollars.
まだ今日のランチの代金をもらってません。
We haven't received payment for today's lunch yet.