Conditional formatting using icon sets across whole sheet

Hello one and all. I am trying to create a preferred supplier based on lowest price. I have attached the test sheet. You will see that I have had some success using a dedicated "preferred" column to show me which is best. I am happy with this but then I found icon sets in conditional formatting and like the tick icon to also show who is the cheapest. Again you will see I have managed this but only on one row only.
I am unable to figure out why I cannot highlight a whole array to speed up this process.
I would like the tick to show in the lowest price cell for that given supplier and be able to do this "en mass" rather than the only way I can do it which is to highlight the three cells in that size row and run the format.

can anyone help me please. I would think its a basic enough command but my experience is not great. I am still learning with your help..

thanks in advance and will leave good Kudos to any contributors.