A trick for the warehouse A/B/C issue is to add about 4 of each part from different MFG to the cart, then see which ones are from the same warehouse and remove the others from the cart.
Easier to do with parts where you trust more than one brand name.
just use the feature that aggregates the shipping locations and tells you what is cheaper. Sometimes the .40 cent more part is located 3000 miles closer to you.
