Should your post office not have these stamps on hand, they can be ordered directly from the postal service's website (HERE). "Forever stamps," they will be sold in sheets of 20 (5 of each design) at the current postage rate of .45 per stamp.
You can bet I'll be buying them...and finding many reasons to send a card with one of those fabulous directors' faces affixed to the upper right-hand corner of my envelope.