Prices define how much and how often to charge for products. This includes how much the product costs, what currency to use, and the billing interval (when the price is for a subscription). Like products, if you only have a few prices, it’s preferable to manage them in the Dashboard. Use the unit amount to express prices in the lowest unit of the currency—in this case, cents (10 USD is 1,000 cents, so the unit amount is 1000).
As an alternative, if you don’t need to create a price for your product, you can use the amount parameter during invoice item creation.
To create a price and assign it to the product, pass the product ID, unit amount, and currency. In the following example, the price for the “Gold Special” product is 10 USD: