An asshole who preorders/buys an item as soon as it's available and resells it at a higher price point than the item originally sold for. Usually is fat, lazy, or has no actual job.
Johnny: I went to Gamestop to get the new Destiny game and they were out of stock and I had to buy it from a scalper.
David: What an asshole, preying upon innocent people wanting to buy something that they find interesting.
Someone who purchases large quantities of goods (usually tickets) early with the sole intention of re-selling them at a higher price at a later date (closer to the event).
Seedy looking guys outside stadiums avoiding police and trying to sell tickets to baseball/football games which are about to start.