It's not a "trick" -- it's a consequence of dynamic pricing and how efficient supply chains are now. You're effectively running volume arbitrage to even out in

It's not a "trick" -- it's a consequence of dynamic pricing and how efficient supply chains are now. You're effectively running volume arbitrage to even out inefficiencies in seller's upstream suppliers. Or, to put it another way, the seller's profits (margin*volume) can often be the same on smaller package (even for cheaper per weight unit) as larger package (for more expensive per weight unit).