Comparing 3 sheets to find a cheapest price in one colum

Hi, this is my first post here, i'm trying to develop a spreadsheet that will act as a price list for a range of samples.

We deal with 3 suppliers and they all have varying ranges of products, they should all be the same price for matching products. However, I would like a way to go down the sheet and see if one supplier is cheaper than the other, then for that amount to be added to a 4th sheet with a formula adding on our profit and VAT etc.

The other problem I'm having is that the suppliers have separate products from each other and how to import them into the same sheet.

I've attached a copy of the 3 sheets in one excel document below to give an idea of what i'm looking at.

Any help would be greatly appreciated.

Thanks.