Well, I picked up my first Postal Note last week -- at a coin show! I decided it would be nice to have a representative example, so I made a spontaneous buy.
This has First Day of Issue cancellations (Feb. 1, 1945) from Denver and both stubs. It is not filled out with a recipient, so I would assume that makes it a philatelic souvenir.
$10 seemed like a reasonable price. Did I overpay?