unique items

unique items

Can i do this:

I wanna make some items that can only bought by one hero,
so if there is already a hero buy this item the other hero cannot even choose this item or even buy it

i dont have WE open right now but there is a function that allows you to add/remove items from a shop, they are under the "Nutural Buildings" Category i think.

and where is the function located?
is it in trigger or object editor?

trigger action=function