Combo Box change event runs with first entry of letter. Can this change?

I am working on a spreadsheet where I would like to allow the user to select an item from a combo box or enter in the SKU for the item. I have a change event that pulls up the price of the item selected. It works great for when I select an item from the drop down but anytime I enter in the first number it grabs the first SKU that begins with that number. Is there a way to only have the macro run when a selection is made or when I finish entering the SKU?