How about used glucometer test strips as a collectible? I had one patient who saved 'em all.
I collect old calculating instruments, preferably HP electronic calculators. I also have a couple of straight slide rules and one of those huge drum-shaped rotating slide rules from 1880.
Ew. Used, with the blood and everything?
This museum at least started as the work of a single man. I’d say it counts as fairly unusual.
I would like to thank the OP for making me feel “normal” (at least for today), as I look around here I see:
~200 antique, American-made, high jewel count pocket watches.
~ 10,000 Wheat pennies.
~80 English-made, Brass grease guns (they came in the toolkits of British motorcycles).
I have so many NOS (new old stock) British motorcycle parts that I had to rent an office/storage building to hold them all.
~20 Triumph Bonneville (650cc paralell twin) motors and ~35 Bonneville cylinder heads.
Why yes as a matter of fact I am single, why do you ask?
Unclviny
Aye, and may you remain so for ever and ever. 
Yep. Granted, he just collected his own strips.
I used to collect the wrappers from sugar packets–you know, the ones you get in restaurants and such. I had more than a thousand of them from all over the world.
A friend of mine saves corks from wine bottles because her mom told her they’d be worth a fortune. Um…are they?
Eh, that’s not so odd. As a kid you come across such a variety of kid-appealing erasers that it’s not hard to eventually wind up saving some, then seeking out more and winding up collecting them. (Why yes, I did have a small collection of erasers as a kid - my piano teacher let you choose one from a mix of incredibly diverse ones if you did well during the lesson.)
I collect coffee mugs from places that I have traveled to. It’s not really very unusual at all, but I don’t often get a chance to mention it, so now I am. Favorite coffee mug: The one from Carhenge.
My SO collects supermarket loyalty/reward cards. If we’re travelling, he’s already researched the stores he’s never been to. He’ll stop at these locations, fill in some bogus demographic information, and walk out with an addition to his collection.
One of my coworkers collects barf bags (yes, unused) from around the world. He’s got them decorating his cubicle walls. We’ve got people from various countries in our department (plus international offices) and they often bring them back from wherever they travel.
But do you actually own a Bonny?
I got an abacus (not an antique, got it at the Boston Museum of Science) and a slide rule I found in the basement of my house! That rotating slide rule sounds wicked cool, though.
For a while as a child I collected plastic flatware. Don’t ask me why. But my dad would bring them home from work for me sometimes.
I also had a bunch of the tags from Salada tea bags, because they had sayings on them, kind of like fortunes from fortunes cookies.
Apparently one of our neighbors saved every monthly commuter train ticket he ever had, going into Chicago every day to work for I don’t know how many years. I wonder if he missed the new ones when he retired.
Cynthia Albritton “assembled” a notable collection of plaster casts.
I collect Bakelite desk sets…
I have a friend who collects souls. He has a standing offer of $10 cash for anyone willing to sign a contract giving him the ownership of their immortal soul. The way he put it, if there is an afterlife, then he has souls to bargain with. If there isn’t, then chances are good that at least one of the people who sold his soul will become a born-again fundamentalist later and want to buy it back – for any price. Either way, he can’t lose.
No,
I have a 1952 Triumph TRW (500cc SV twin) and a 1936 BMW R2 (198cc upright single).
Unclviny
There was a guy at my junior college who bought souls. How many does he have?