Split Block Pricing
  
You know how you buy a bulk pack of 200 cans of Peach Citrus Fresca for $100, but the individual cans say "not for individual sale?" Those labels are meant to prevent split block pricing.
The term itself refers to what happens when you break a larger order into smaller ones. Instead of getting a single price for the whole lot, smaller chunks get individually priced to particular buyers.
So...with that Fresca (and ignoring the label), you sell 25 cans to your cousin for $1 a can. Then you sell 50 to your friend Merrill for $0.75 a can. Another 125 goes to Fat Eddy for his annual family picnic; he paid $0.90 a can.
The price per can isn't stable across the whole supply. It varies from sale to sale. It's relatively easy to figure out though. ($1 x 25) + ($0.75 x 50) + ($0.90 x 125) = $175, which is the total amount earned by selling all the cans. Now, divide that by 200, and you get a per-can price of $0.875.