Add to my Function / formula
 

I have created a drop down list and added a formula to show me the cost of an
item eg; pink slippers when that is picked from the list the price appears in
the next column..that is all working fine.....=IF(C3="","",VLOOKUP(C3,'Sheet3
(2)'!A3:C152,2,FALSE))
I've been trying to add another formula to this for inventory. So actually
what my question is.
How do I create a list along with a formula so when I pick the item out it
will put in the price, and minus 1 or however many sold, to give me a count
of what I have left in stock.
Is this possible, if not any suggestions? Thank you