I have a working 1920's Duncan-Miller meter I bought at Chicago a few years back. Haven't managed to restore it yet... still on the "round to it" pile.
I got an interesting reaction from the TSA when I sent my carry-on through the x-ray machine with it inside.
1st TSA Agent: "Sir, we are going to need yo to open this bag"
Me: "No problem sir, I suspected you might"
2nd TSA Agent (running x-ray machine): "Before you open the bag... is it a parking meter?"
Me: "Yes, I bought it at a coin-op show."
2nd TSA Agent: "Pay up Steve, I guessed it!"
Opened the bag, showed them the meter and on my way I went.