Kabuto king effect
When a person or a bunch of jerks buy up all the cheapest stuff before anyone else even notices, then when everyone else realizes they want it, there's nothing left and the price goes through the roof like a f***ing rocket.
A guy buys all the cheapest sneakers online before the trend starts, then sells them for ten times the price.
A group of kids grabs every single cheap snack in the vending machine before the whole school gets hungry.
Some rich guy buys all the cheapest concert tickets before the band even gets famous.