Actually, prices for the old computer junk I have laying around has gone WAY up so I probably should just list that.
I once sold an Apple 1200 baud modem to the Keck Observatory in Hawaii.
I asked them what possible use they could have for such an ancient piece of equipment, and they said that they had an experiment running with the same modem, and the wanted to have a backup in case of failure, and didn’t want to risk some software incompatibility with a different device.
I also sold my Parametric Equalizer to Ray Kimber. I said are you the “Kimber” of Kimber Kable, and he said “yes."
Okay, I’ll imply it’s specifically for an iPad. The brand will be the one on the package from Walmart. I’ll buy another 3-pack to get the name and I’ll transfer the stylus directly into the envelope so I can honestly claim it’s new. Not significantly sleazier than the ad in the OP where the seller is listing at more than 1.5 times what the maker charges and insane shipping ($69.85 to the UK!).
I used a lot of sucker cable at another job, but my conscience won’t let me get into that racket on my own. FTR, my customers believed all the horseshit claims so we provided a brand name, but mostly the low end stuff because cable is cable.
Do beware of cheapie chargers. The specs for USB (I don’t know about Apple) are more complicated than the casual observer might guess, and cheap chargers won’t comply. Even cheap cables can cause problems. It’s different than the old days when a wire was just a wire. A Google engineer has famously reviewed USB-C cables, and in one case a cheapie cable fried his equipment.
I have no doubt the same kinds of issues could occur with third-party chargers for Apple devices.
#4 is simple, most of the time it is due to a book having some sort of collector value, and two sellers both using a program that will set their price as the highest.
My “claim to fame” in this department was selling an old Russian folk tale book to Pixar Studios, and a book that was purchased by its own author. I won’t say what the latter item was because this was a nonfiction book that was a decent best-seller that came out around 2000 and is still in print; my guess is that for whatever reason, she wanted a like-new copy and didn’t want to pay $35 for it, so she hopped over to my board and paid $15. As for the book that went to Pixar, if they come out with a movie called “Ilenka” in the years to come, I had a part in it. 
As for obsolete computer equipment, I found this totally cool video last night.
Hey! I used to know the guy who wrote that software. Steve Bjork wrote a lot of stuff for the CoCo. He also wrote the licensed port of Zaxxon. Fun with artifact colors!
People used to use automatic pricing mechanisms, that would price their item above what they could buy it for. Either so they wouldn’t get orders for items they didn’t have in stock, or so they could buy it if they made a sale (don’t remember which). Back in the day, these automatic pricing mechanism would sometimes bid each other up to insane amounts if there was no real item underlying several sellers.
That’s been fixed now: people don’t do that anymore. Perhaps they only float up to a limit.