This is slightly off-topic. My ex-employer used to run the warehouse management for a cyber company whose business model was entirely based on the 1/3 – 2/3 ratios mentioned earlier. The idea was to make people buy products at enormously inflated prices (often at over 10x the retail value) and offer rebates on most items equal to the cost … and have free shipping.
Well, apparently the 1/3 – 2/3 logic falls apart at infated prices.