Bet it's people selling beans they've picked up abroad or off a mate... Don't grow, don't know how to store them properly. Chances are from eBay, the persons had the seeds for ages, found them cleaning up and sold them.
I make a living from eBay, so trust me when I say that 99% of the time it's not worth buying from there. I sell everything at the most competitive prices (I sell designer clothes) and I still make a profit or I wouldn't sell it.
Must admit looking quickly I am tempted at the prices haha
When it comes to science, stick with professionals