I've read the comments on primitive+ requests and that you cannot support ressources from TCs because they are not content of the dev kit.

Maybe you could support ALL items from current and future TCs by implementing a "Generic Sell Table" and a "Generic Buy Table".
Logic simmilar to the admin table custom blueprint logic.
Admin places the table and inserts ressources he wants to be sold/bought by the table and enters a price for each ressource.

Of course this table engrams should be hidden by default, only the admin should be able to define prices ;)

What do you think of this?