This term should be familiar to anyone who has bought prime tickets to a big game or concert at the last minute by making a deal with a guy who yells "Got two here!" in the stadium parking lot. The guy in the lot bought the tickets earlier at the lowest possible price. He has no desire to attend the event. His goal is to negotiate a deal at a higher price from a desperate fan and to pocket the difference as profit. It is a common practice despite local laws that can send the seller, and sometimes the buyer, to the pokey.
That is the essence of the "scalp." The same thing happens in the markets, more or less, and the scalper doesn