Add a Shop to sell things

one Problem for me is that i’m pretty far in an have thousands or runes/gems/materials that I don’t need or want cluttering up my inventory.
I could transmute them but i’m using those resources to breed a new team, and the cost would be ridiculous.
I could drop them but that would take time i’d much rather be playing.
the ability to sell them even if just for peanuts would enable me to clean up the inventory and use the resources for other things.