Adding price to different unit of measure for expected price

So I created this form to help each department see how much each item is before approving the items. Each item can be chosen as each, box, or case depending on how much the staff needs. I wanted the price to populate when each, box, or case is chosen. So if one AAA battery is chosen (each) the expected price would be 1.29, if one box is chosen the expected price would 5.29, if one case is chosen it would be 10.29. Is there a way to do this? I didnt know if i should do a drop down or have the staff type in the response. Please see attachment.