What is the price for 1 US postage stamp?

The price of one US postage stamp sufficient to mail a one ounce letter to any destination within the US is $0.44. That price is likely to increase soon.

Note also that there are a great variety of US postage stamps available for various purposes. You can buy a single stamp with a value of $0.01, but you can also but a single stamp with a value of $7.80, $10.00, even more.