The can be purchased at the Post Office. Currently you can get one for 44 cents. The Forever stamp is worth the cost to mail one ounce of first class mail. It will always be worth that much...
Yes. I believe you mean 20 cent ($0.20)stamps that were issued between1981 to 1984. If you mean fraction stamps the answer is yes. The U.S. issued fraction stamps called "Proprietary" stamps in 1898...