Yep: when I had the chance, I kept an oldie that a friend took out of his grandparent's house after they passed on, close to 30 years ago.
It doesn't look like I'll get rich off of E-Bay, then, since I've only got two transmitters (run on 6 V DC), and I think three receivers. The transmitters have the same sort of V-shaped antenna, but aren't marked on the outside of the boxes. I have three old door mechanisms; the oldest-looking one is a "Auto Magic" door operator from the United States Motor Corporation of Oshkosh Wisconsin. There are newspaper ads from 1957 offering one as a prize in a contest, apparently. The serial number on one of mine appears to end in "...54", which makes me think that it might be the year?