I've got 3 on my list.

1. BT-PAN Access Point - Kinda ridiculous, but I'd like to have one. I've also found a few BT-PAN-enabled dial-up modems, but I'd have no way to connect those up. Some of those could even be connected to USB printers for wireless printing. Not particularly useful anymore, I just find those devices interesting.
2. Dot matrix printer - This one isn't even as ridiculous. I really love that sound and how the text they print looks. Sadly, if I am looking for new ones, a basic 9-pin Epson dot matrix is around €200. But the ribbons are cheap as chips. In fact, often even cheaper. Just imagine casually handing out a document printed on dot matrix to someone nowdays.
3. Nano pocket drone - Something like FQ777-124. Maybe a toy like that is a bit childish, but it still can be fun. In fact I already tried to order this one. From 4 different sellers, twice on AliExpress, twice on Amazon. I never got it :(