During the famine in Egypt (Bereishit chapter 47), Yosef made sure that the price of grain would not become exorbitant. According to Jewish law, the courts have an obligation to supervise merchants and make sure they do not wildly overcharge. The primary concern is when we are dealing with staples such as wine, oil, and flour. In general, profit may not exceed one-sixth (approximately 17%), after the costs for labor and expenses are deducted. Of course, the courts must set price caps for all the merchants equally, without discriminating among them.
What sanctions can be used by the courts against a merchant guilty of price gouging? According to the Rambam, such a merchant is flogged, while according to the Shulchan Aruch he is fined. There is an additional weapon available to the people – a consumer boycott. Indeed, we find an example of this in Responsa Tzemach Tzedek HaYashan. In a certain town, the fish merchants all raised their prices excessively. In reaction, the Tzemach Tzedek instructed the people not to buy fish. The boycott continued for a number of weeks, until the merchants lowered the prices. This was even though the boycott infringed on the mitzva of enjoying and honoring Shabbat. The Tzemach Tzedek pointed to a precedent for his ruling. The mishnah in Keritut records that when the prices of a particular bird offering became prohibitive, Rabban Shimon ben Gamliel allowed a woman to offer one bird to cover a number of obligations.
However, the Chatam Sofer rejected this proof for the boycott. He argued that in the case of the woman who was permitted to offer one bird, she had the possibility of offering the additional sacrifices at a later time. In contrast, one who did not eat fish on Shabbat could not make it up. Additionally, a poor person who cannot afford fish is not required to eat it on Shabbat, while a poor person is not completely exempt from sacrifices. Thus we see that the two cases are different.