Creating a Formula Using Picklist

I have in a spreadsheet a summary of different items that we would purchase in a package. What I'd like to do is lookup a particular name with a lookup table in a formula and sum what the cost would be if all the pieces were purchased separate vs in the package to see the savings.

The formula I'd like to be in Column R of Kits. The parts and prices for the lookup table to reference are in the tab Parts & Prices. I do realize I have some parts to add to the lookup list.