Soda bottles. Enough said. I went from ten years and eight bottles to put in my wooden Coke crate... to 45 bottles, plus 24 in my full Coke crate. All it took was two weeks, and I was finding things to buy - that Paypal is the death of my bank account! I've tried to collect every city in Louisiana, and it all started with one RC bottle from Lake Charles. The other seven were out of state (Corpus Christi, Hollywood, Quincy FL, all Coke bottles), and a Coke Blak and Barq's Floatz bottle.
Any other weird collections that you now have thanks to eBay? Signs may be included!
Watches and Wedgwood. For the latter, I can buy designs intended for different national markets, which can differ substantially from what we're used to seeing in the US.
I do have 2 traffic lights bought from eBay. I rewired the lights so I could operate each light independently using equipment normally used for my Christmas display lights.
Signs and maps.
Computer junk.
Old Christmas lights, particularly C-7 and C-9 strings from the 1940s through the early 1970s or so, the ones with the twisted red/green wire and the dark brown/black sockets.
Music from Japan. Not J-pop or stuff like that (although I have one or two Ayumi Hamasaki CDs), but video game soundtracks, eurobeat (made in Italy, sung in English, released in Japan), stuff like that. Before I began working on cars, I had a much bigger music collection. It's still pretty big and diverse, but many of the rarer items are gone. My tastes have also changed somewhat in the past few years, going towards alt rock and electronic genres like drum & bass and UK dubstep, which is more chilled than the Skrillexes and Excisions of the world.
Don't know about a "collection" per se. I found a board game I remembered from when I was a kid. My fifth-grade teacher had this in the classroom and a group of us used to take it to the cafeteria every day to play during lunch. Some folks here may appreciate this. The game is called Computer Rage and it's a race-style game where the object is to be the first player to move all four of your "programs" from "Input" to "Output." The game has three binary dice (containing only ones and zeros, obviously) that are color-coded to indicate the "ones," "twos," and "fours" positions (so if you roll 1-0-1 it may be a 5 or a 3 depending on which two dice show the ones).
Perhaps the geekiest board game ever, and almost certainly the only board game that ever had a space marked "Output Queue." The "Interrupt" space seen in the middle of the board below is a spot for a stack of cards (similar to Chance or Community Chest cards) you draw when you land on a space with a lightning bolt. When you pass through those question-mark spaces you roll one die to determine which path you follow.
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fwww.rarityguide.com%2Fmuseum%2Fimages%2Fcard_and_board_games%2Fcomputer_rage__1977_%2Fcomputer_rage_board_game_creative_computing_1977.JPG&hash=cee971f888651b9a303952d42eae7f493fc1181a)
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fcf.geekdo-images.com%2Fimages%2Fpic614631.jpg&hash=9d7bc95d8c24bf982956ba292692f6f667c79c1f)
Otherwise, my main purchases on eBay have consisted of music, old mono LPs and the like.
I have nylon wire tires in 13 colors.
Bought all the Kliban cartoon books I wanted.
And not really a collection, but I found some aftershave/cologne I used in High School that hasn't been made for 30 years. Pretty funny what all is on Ebay.
Note:
while Ebay STRONGLY encourages linking to bank account and/or credit cards, I am cautious about that as it just seems INEVITABLE that no matter how robust their security is, sooner or later they are going to get hacked, and hacked bad. I link to a low limit credit card and a separate checking account with a low balance.
The only collection that exploded was signs. I've added a couple of coins as well.
If you ever want medieval armour from ebay, look me up!
My license plate collection exploded because of eBay. Before eBay, I was relegated to antique shops and garage sales. I found out that there was in fact a plate collection group because of eBay. Before that, I just thought that I had odd interests.
Galaxy S3
Just my collection of official state highway maps (I prefer the DOT maps...not a huge fan of gas company maps).
Traffic signs & signals! I had one traffic light and only a handful of signs before I entered college & discovered eBay.