Regarding NES/FC carts, I've heard stories of the following:
- People going to flea markets (those unfamiliar with the term, if colloquial: open markets where random people are selling items of random sorts), finding NES carts with no prices on them (intentional), and when asking the seller how much they want, the seller goes onto eBay or Amazon and quotes them a price slightly higher than whatever the highest price there is -- and anything they don't end up selling they put on eBay anyway
- People going to flea markets, waiting outside until they open (e.g. 0600 in the morning), buying up as much of other people's stuff as they can, then proceeding to open up their own table/booth and selling the same items with a 300-500% mark-up
- People trying to sell super common/generic carts like Super Mario Bros/Duck Hunt for US$40
And don't forget (I'm mainly pointing this out for non-North Americans): "haggling" is uncommon/considered rude in the US/Canada, including at flea markets, so what you're quoted or what you see on a sticker is what you should expect to pay.
One of the guys who goes to flea markets and has experienced all this shit is
Pat the NES Punk. Check out his Youtube channel, particularly these videos:
I'm sure Martin Nielsen of NESWorld would have quite a number of stories/commentaries too, since he actually goes to flea markets in Turkey every year (or he used to, not sure if he still does) to find weird pirate carts and "oddities". Although in Turkey, if I remember right, you're expected to haggle at such markets (I'm not a good haggler, I find it a bit uncomfortable, like trying to talk someone into buying something -- I'm no good at it).
The same is happening in the arcade PCB community, with this added gem: people literally hoarding PCBs (i.e. trying to get as many of one kind (particular game, particular company, particular series)) with no intention of playing them / using them, the sole goal being to create a niche market where they're one of an elite few who has a particular PCB just so they can sell them for super high prices in the future. They won't send the boards to MAME folks to dump for emulation or anything, just flat out hoarding for future financial gain (or so they hope).
There are also people who purchase retro hardware (consoles, games, everything) with the view that what they're buying is "an investment" -- literally they buy whatever they buy and lock it away in a box somewhere with no intention of it ever getting used, being resold, or anything else. (Similar to above, re: hoarding, but they try to justify it by using the word "investment").
All of this shit pisses me off. For whatever reason the past 5-10 years (well it's been going on for longer than that, but it's been especially bad with retro stuff in the past 5-10) there has been a tremendous increase in the number of idiots who think up ridiculous ways to "get rich quick" off retro things and conclude that somehow they can make a living off of this. I'm not going to sit here and blame the shitty US economy because there are similar stories in other countries, but it seems to stem from laziness. I'm a guy who has all sorts of pre-requisites to work somewhere due to health-related complications (ex. I have to work from home / 100% remotely), but even I'm able to find work. It's a lot easier to just get a job, even part-time, and have steady income that way -- then spend some of what you make on enjoyable hobbies.
I wish there were more people who understood the whole "retro community" concept. For example, the fellow who showed up on the forum here recently with FDS/Famicom problems, where I opted to send him my hardware (including a free FDS RAM adapter), paying for shipping + return shipping out of my own pocket, just because I wanted to help someone. No monitary exchange involved -- the goal was to solve a problem/help someone, not make money. I guess I'm a dying breed of person, one who just wants to help people and really doesn't like bringing money into the picture.