I can't speak for cargo skins specifically, but when some "asset" sells for an abnormally high price, there is usually something else going on. It's like when a condo which would normally be worth 200k sells for 380k, it can be a way to turn dirty money into a "reasonable" sale. Sure the seller has to pay taxes and such on it, but if there's no strict know-your-customer requirement, you can accept money from any source.

The usual arrangement is that the seller inflates their price a lot, and then the seller provides the product plus a kickback to the person who wants to launder the money. Now the launderer has a real, valid asset, plus optionally some of the overpaid amount in cash. As long as the buyer reports the income and pays taxes, now the seller has laundered the money. I am oversimplifying somewhat, but that's the idea.

A lot of properties have been sold by a certain high profile American politician that way in the last decade. That's a fascinating place to start studying the scheme.