Select Case or IF?

I've got a form with the following items for a printing estimator app

• Quantity (This can be any quantity)
• Size (This is a combobox with 5 options e.g. A5, A4, A3 etc)
• Paper (This is the type of paper used)

Lets say the user enters 2000 as quantity, A5 as paper size and gloss and Paper type. I would like to calculate these and then place the cost into a label. How would I go about doing this? I was thinking a Select Case but then it seems so complicated