I would never do anything like I suggested; however, as a buyer, I would be happy to pay a little extra for a soap I want that is no longer available. It's not like the time and effort it would take to acquire, pack and ship should go unrewarded.
We sell razors that cost very little money when new for "big bucks" today on BST. Wouldn't this scenario be somewhat like selling a "vintage" soap?
Nope. Gouging, big markups and charging outlandish prices for anything on the BST will get called out. Finding a Superspeed for $2 in the wild and reselling for a fair price is fine. Charging $100 bazillion for it is frowned upon here, and should be done on eBay instead.