Grey markets sometimes develop for video game consoles and titles whose demand temporarily exceeds their supply causing authorised local suppliers to run out of stock. This happens especially during the holiday season. Other popular items, such as dolls, magnets and contraception, can also be affected. In such situations, the grey market price may be considerably higher than the manufacturer's suggested retail price, with unscrupulous sellers buying items in bulk for the express purpose of inflating the prices during resale, a practice called scalping. Online auction sites such as eBay have contributed to the emergence of the video-game grey market.