It's possible that the seller is taking a loss on ebay sales in order to move money out of China. It's also possible that they are intentionally losing money on eBay as a means to wash funds gained through credit card fraud. AKA "Triangulation Fraud".
Shortened version of the story from the video I posted above:
Someone buys the bass from eBay, then the seller uses a stolen card to purchase it from "Glarry" who drop ships the item to the buyer. When it's a small amount of $$$ and no-one appears to be taking a loss the system isn't very motivated to intervene.
Unfortunately the sellers can't ramp up volume without raising alarm bells, which is probably why these deals keep dropping out.