Shopping w/o inventory

Hi again ppl i am lil out of ideas on how to do this thing :

i want to make some units "buy" their spells but those unit are supposed to be without the inventory i was thinking to do something like "selling" runes and the upon activation to add the spell but im not sure how to do that so if somebody can help ill be thankfull

sell dummy units instead of items, and remove the units as soon as they are created.

ehm i think that would compromit the scoreboard ...

i'm testing right now a "add inventory near shop" thing hope it works fine

Edit : actually that idea might work better than mine xD

You should do it the way that Here-b-Trollz said, adding inventory near shop my be a bit buggy and not very smooth

You can create a custom inventory with zero inventory slots.
That way unit can get only runes but not standard items.

i tried this but i can't :S it doesn't let me put 0 inventory slots

Hold Shift + Enter when you open the field, that was it takes 0 as an argument.

Another idea would be adding abilities to your shop that are based off on the neutral spell 'Aans'. This ability allows you to specify gold and lumber cost for casting it and it allows multiple instances of itself on a single unit since you can change the order.
But you would have to trigger the effect of your items because 'Aans' has no effect on itself . So as long as you don't plan any fancy stuff Cohadar's solution will be probably most appropriate.