The other problem are people doing price arbitrage. You find the item on eBay and think to yourself, "cool, I'd rather patronize a small business" - but as it turns out, the item is drop-shipped from Amazon, Walmart, or the like.
Yep, had this happen to me a couple of months ago, for a bike component. Incredibly annoying, since they still marked up from the Amazon price!
I recently had something very similar happened to me, and then the seller accidentally sent me another weirdly expensive item by mistake. Unfortunately it's a large heavy part from a ride lawn mower
Just got hit by hustler university
This got me the other day, and it had me cracking up, they just put my shipping address and and checked out from Walmart. $5 lesson that Walmart actually sold what i wanted and i should have checked there first.