Welcome back, it was more than 3 years ago that you posted last. As to your question, it involves the Fourth Buddhist Precept.
learn religions. com explains that the 4th precept translates to “I undertake the precept to refrain from incorrect speech”, “Zen teacher Norman Fischer says the Fourth Precept is ‘I vow not to lie but to be truthful'”.
The entry further explains: “In Buddhism, being truthful goes beyond simply not telling lies… it also means using speech to benefit others, and not to use it to benefit only ourselves…
“Speech rooted in the Three Poisons- hate, greed, and ignorance- is false speech. If your speech is designed to get something you want, or to hurt someone you don’t like, or to make you seem more important to others, it is false speech even if what you say is factual. For example, repeating ugly gossip about someone you don’t like is false speech, even if the gossip is true”.
You asked: “Is raising the price and then discounting the price of the product included in the violation of the fourth Buddhist precepts?”- you mean raising the price of an item and then discounting it, so to give customers the false impression that they are getting a better deal than they are really getting, and in so doing, motivating customers to purchase the item and create a bigger profit for you.
Seems to me that yes, this practice, although common, is in violation of the Fourth Precept because it involves deceit. To be truthful and beneficial to yourself and to other people.. you have to practice what is uncommon, which is not easy, is it?