So all your tomato products would get bid as a single bid. After you have determined your categories, it really works like a line item bid. Total aggregate cost for those categories of equal product wins the bid. Components of services. You will get the lowest cost from prime vendor across the full spectrum of product that you purchase.
Limited prime is the next lowest cost, followed by category bid.
Line item will usually be the highest. However, a line item bid for a truckload of canned crushed tomatoes will get a heck of a price. On the other hand, take a category award bid request on PCs. A particular customer wanted a lot of PCs in total, but only 40 cases at a time. We didn't bid it.