I have thought of this idea for years and tried it out on eBay last Christmas season:
Took about a dozen run-of-the-mill Antique Xmass PC's and put them on self peel & stick mailing labels which I had printed reproductions of old address sides of several different PC's.
Examples:


Listed them on eBay Under a title of something like: "Mail an antique post card...."set back waiting for orders to pour in:
Went over like a lead balloon, not one order. Price was $1 or so with 79c postage. Even supplied the modern forever PC stamp!
Mailed one to my brother last week and he thought it was a cool idea, receiving an antique PC in the mail, but then which brother wouldn't!