Scalping in the video game world is when someone buys up the stock of items they have no intention to collect or play only to sell them at a much higher price. They bank on the fact that if they buy everything, they can then set a high price so people that actually want the items for their collection will have to get it through them.
It's not illegal to do this kind of thing, but it's very frowned upon in the gaming community. The only way to control this would be for gaming companies to re-release items that are becoming rare due to these re-sellers. That, or they could enforce a one per customer rule strictly for offline items at stores. It's getting to a point where you have to be lucky and on an ordering website as soon as an item goes up or you're going to miss it and have to pay much more for it.
One of the more recent problems with scalpers was for the Fire Emblem: Fates Special Edition for 3DS set. What should cost only $80 retail now is going for close to $300 because all of the copies were sold out within the first day or so of sales. There were also preorder mistakes that were made. It's a giant mess, and a lot of people that actually wanted the set are now forced to go without if they don't want to pay the ridiculous amount of money.
As a gamer, it is a shame to see that these people are extorting people like me. The way I deal with this is that I just don't care about collector items and if a game is super rare I'll buy it digitally if possible. If I can't do that, I wait until there's a good auction up or something because I will never give my money to a scalper!
1 - http://www.nintendolife.com/news/2015/02/talking_point_the_limited_edition_battle_with_ebay_scalpers_can_be_tackled_more_efficiently_by_nintendo
2 - http://attackofthefanboy.com/news/fire-emblem-fates-special-edition-pre-orders-cancelled-gamestop/