People make money selling Amazon items on eBay. It isn't hard to spot, though.
Mark broke off the antenna on the backup camera on the camper. No big deal, I broke it off before while washing the camper. I reattached it with duct tape, but this time it was really broken. I went on eBay and saw a two-pack of antennas for sale for $12.77. "Last one! 16 sold!" it said. Seemed like a good price so I clicked. It never came. The seller said it was lost in transit, so they gave a full refund.
The reality was, they forgot to order it as a "gift" on Amazon. That's how arbitrage works. They list something for sale on eBay for a few dollars more than what it sells for on Amazon. Since they are a "Prime" member, they get free shipping. Someone "buys" their item on eBay and they then go to their Amazon account, and "buy" the item as a "gift" for their buyer and then pocket the difference in price.
One could, I suppose, even program a "bot" to do all of this automatically - and I suspect that is what happens. Perhaps the bot glitched in this case and "forgot" to order the item on Amazon - or it was out of stock. We'll never know. Of course, the "seller" gladly issued a refund and suggested I reorder the item. I got suspicious at this point. How could the item be "lost in transit" when eBay shows it was never shipped? I was a victim of arbitrage - or attempted arbitrage, anyway.
It isn't illegal, and it isn't really immoral, either. When I clicked on "buy" on eBay, I thought I was getting a good deal, Little did I know the item was for sale on Amazon for $7.50 for the pair. I've been "stung" by this a few times, and you can tell when it happens as the package arrives from Amazon, not the seller, and there is a "gift receipt" inside. You've been arbitraged!
Of course, the easiest way to avoid this "problem" is to open both Amazon and eBay windows and cross-shop the item in question. You'll figure out pretty quickly whether someone is arbitraging on eBay. Hint: Often the item titles are identical - making searching on Amazon for the same product advertised on eBay much easier.
Often the listing is word-for-word what was on the Amazon listing. Perhaps another bot "scrapes" Amazon and automatically creates eBay listings. Why not? Another tipoff is this "Last one! Over 25 sold!" or something like that. I seem to be buying the "last one!" whenever I am arbitraged.
Also, these are often inexpensive items - usually under $50 or so. They mark them up by a few dollars, which seems pointless, until you realize that if you have a 100-bot army scraping Amazon for listings and then processing the sales, automatically, you can make an awful lot of money without a lot of effort. That is, until everyone and their brother gets in on this deal. At that point, you sell seminars and kits on how to arbitrage on eBay. And yes, I have seen ads for this nonsense.
Is there any harm to this? Like I said, I was the chump for not cross-shopping with Amazon. The problem with this technique is that everyone is doing it and the everyones have set up multiple eBay accounts, so you end up with hundreds of nearly identical listings for the same item, over and over again, which tends to "bury" the real listings at competitive prices. This makes eBay harder to shop on, which in turn means people get turned off by eBay. The real risk is to eBay itself, although they make a commission on each item sold, so maybe they don't care either, if they end up being merely a reseller for Amazon.
Time was, whatever was sold on Amazon could be found on eBay for a few dollars cheaper. And sometimes this is still the case, although I think less and less lately, and arbitrage is part of the problem. Of course, Amazon is loving this, as they make sales, and it degrades one of their largest competitors. If people turn away from eBay, so much better for Amazon.
But sometimes, you find deals that beat Amazon. We bought a portable safe from masterlock for our trip. It is ABS plastic and has a cable so you can lock it to a beach chair or under the seat of your car. Not burglar-proof, but it deters the smash-and-grab set. Amazon had it for $19 and eBay wanted a few dollars more (last one! arbitrage strikes again!). Home Depot had it for the same price as Amazon. The kicker was, Amazon wanted $12 extra to deliver it by today, while Home Depot had free delivery by today (it is out for delivery according to FedEx). Home Depot has a warehouse nearby, so I guess they have an advantage. Either that, or it is one of Amazon's games, designed to get you to pay extra for "fast shipping" when half the time, slow shipping arrives at the same "fast" time.
Who knows? What is interesting to me is how we are constantly manipulated in the marketplace. And with the Internet, well, there are so many more subtle ways to manipulate us these days!
Arbitrage! Beware!