Newbie to the game and I just finished the initial tutorial. Went to the city, purchasd some new items that were available, like the sling, leather armor, etc. Where do I get these item cards from to use with my characters, I didn't see them in the original box set? I even looked online and I can't seem to find any just item cards sold anywhere?

Those items should be in the default items deck for the core game, Act 1 I believe. Have you checked to make sure you aren't missing any components?

As you can see here: https://wiki.descent-community.org/Descent:_Journeys_in_the_Dark_(Second_Edition)#Act_I_Items

all cards you mentioned should be in the base game. If not, your base game seems to be incomplete.

Thank you, I don't know how I missed them before but I do have them.