The Ortlieb panniers makes the most sense but I'm throwing in my budget solution.
I couldn't find any milk or metal crates so I went with wicker baskets zip tied to my racks.
The front one is actually a planter basket I sprayed black.
I can carry a lot of groceries with this setup, but it is top heavy.
I'm 190 pounds so the extra weight doesn't bother me so much.