Compare linked products

Hello,

I am currently trying to do some analysis on the pricing on both our branded products and own brand products.

I have a mapping spreadsheet which tells me what branded product is equivalent to what own brand product in the form:

|| Branded Product ID || Equivalent Own Brand Product ID||

I have another spreadsheet which tells me the price point for every product in the range at every store (there are regional variations) in this form:

|| Product ID || Store ID || Product ID&Store ID || Price Point 1 || Price Point 2|| Price Point  3 || Price Point 4 || Price Point 5 ||

I want to be able to compare the prices in order to determin average savings for choosing own brand. How would I do this incorporating my link?

Thank you.