[REQUEST] - Selling Options as the inverse function of Purchase Options

[Karuna053]

Is your feature request related to a problem? Please describe.
Hi, I would like for my players to be able to sell an item of their possession, and gain something other than primary currency, for example: their HP, and other secondary currencies.

Describe the solution you'd like
I would like a feature where we can set a Selling Option as an inverse of Purchase Option. This is so that merchants can be more flexible and can act as a barter-NPC. With this feature for example, when you "sell" a powerful artifact to a Blacksmith Disassembler, they can "disassemble" it for you and you get 2 Soul Points and 2 Mineral Materials (both secondary currencies).

And the inverse of "Disable Normal Cost" too, for Selling Options:

Thank you!

[Haxxer]

Added in 3.1.0