Wiktionary
n. 1 An unscrupulous and sometimes illegal sales technique, in which an inexpensive product is advertised to attract prospective customers who are then told by sales personnel that the inexpensive product is unavailable or of poor quality and are instead urged to buy a more expensive product. 2 (context by extension English) Any similar deceptive behavior, especially in politics and romantic relationships.
WordNet
n. a deceptive way of selling that involves advertising a product at a very low price in order to attract customers who are then persuaded to switch to a more expensive product
Usage examples of "bait and switch".
Over the last two years, space combat between the New Republic and the Yuuzhan Vong had evolved into a game of bait and switch, each side trying to bluff the other into squandering its limited reserve of power on unneeded defenses and ineffectual attacks.