Stoller [saying nothing that hasn't been said before]:
All commodities (averaging out socially necessary labor-time) are exchanged (sold) for their TRUE value.
: usually true, but not always. I worked in fast food once. Every morning we'd walk literally around the block (maybe a minute away) to a bagel chain, Finagle's. We'd buy bagels there for fifty cents each, take them to our greasy coffeehouse around the block, and sll them for a dollar. Did we put labor into the bagels? If commoditeoies are always sold for their value, then how could the bagel be worth fifty cents before and a dollar afterwards? Did we suddenly double the amount of labor put into that bagel? Hardly!
: If you ask me, the baegls were always worth fifyty cents, and like most fast food entreprises, we were diddling the customers.
The bagels were worth 50¢---even if some numskulls were stupid enough to purchase them for a dollar.
In Marx's view, the lowest price will eventually become the standard price. The place that overcharges eventually goes down---unless they have a monopoly (perhaps on 'diner charm'), or put out enough advertising to create a 'monopoly resting on popular conviction' (Veblen's term). Sam Walton generally proves this rule.