This is how you can showcase the minimum price per brand/category in your feed
In order to display a minimum price per Category/Brand/Color/Product Type, set an action of "Group by".
For example: You wish to display the minimum price per Brand.
Set an action on the brand column of Group By > Aggregate minimum on > Price > Remove the selection of Reduce number of rows (this option will reduce your number of items in the feed and will leave only 1 row per parameter).
EM will organize the minimum price per brand, while your feed will still include all range of available
NOTE: This feature will be useful to you if you want your ads to display the lowest price available in your inventory.