אונאה
Parshat בהר contains many practical laws related to settling Eretz Yisrael. Not only are there laws connected to Shmitta, the Sabbatical year, and יובל, the Jubilee year, there are also rules connected to acquisitions.
The Talmud establishes these rules into the categories of land, קרקע, and מיטלטלין, movable items. The act of acquisition, as קנין, is different for קרקע and מטלטלים.
We are also introduced to the concept of אונאה, which represents price gouging, or overcharging for sales that have been made.
The definition of אונאה, means that one is not permitted to profit more than a שתות, which equals one sixth or around sixteen per cent above the going rate for movable objects.
Regarding קרקע, the Rabbis established that אין אונאה בקרקעות, there is no overcharging regarding land deals. There could be numerous factors why one might be willing to pay a hefty price for a simple piece of land. He might own an adjacent piece of land, or simply that the location of a particular property is worth a great deal to that person.
Regarding every day movable items such as food and basic goods, there needs to be more of a standardized price for the consumer. This is not the case by land.
This is how the laws of אונאה were established by our Sages as reflected by פרשת בהר.