Vloopup VBA help

Hi
Relatively new to Macros/VBA and need some help if possible

First the story
I've created a master Parts file (Name, Description, Drawing, Manufacturing type & cost). In a second sheet I have the parts list (Parent, Component, Qty, Line Cost) and finally a third, which is a pivot table of the second showing the parent and sum of component costs.

What I want to try and do is create an "Update Costs" button on the first sheet, that will check the Manufacturing type to ensure it is an assembly, then find that part in sheet 3 and transfer the sum cost into the cost cell in sheet 1, and continue through to the end of the items on sheet 1.

I'm really struggling with where to start, any help would be appreciated.

Thanks
Craig

I've attached a sample spreadsheet of what I'm looking at