The essential element of a sales contract is the determination of the object, while the price (purchase price) is not always considered an essential element, as the parties may define it explicitly or only indirectly. However, if the contract does not specify the purchase price and does not contain sufficient data to determine it, the contract is deemed not to have been concluded. As with any contractual obligation, the purchase price must at least be determinable; otherwise, the contract is null and void. The price cannot be determined unilaterally. A contractual provision that leaves the determination of the price to one party is considered as if it was never agreed upon.²⁰⁶ The contracting parties may agree that the purchase price depends on the market price of the goods covered by the contract. If a daily price is agreed upon, the buyer owes the purchase price recorded in the official market register at the seller’s location at the time when the performance should have been carried out. The parties may also agree that a third party, such as a professional appraiser with specialised knowledge, will determine the purchase price. If the third party entrusted with determining the price refuses or is unable to do so, and the contracting parties do not subsequently agree on a price but do not terminate the contract, it is presumed that an appropriate purchase price has been agreed upon.²⁰⁷

Special provisions apply to commercial sales contracts. If such a contract does not specify the purchase price and lacks sufficient information to determine it, the buyer must pay the price that the seller customarily charged at the time of contract conclusion; if none exists, then a reasonable price must be paid. A reasonable price is considered to be the market price at the time the contract was concluded; if that cannot be determined, the price will be set by the court based on the circumstances of the case.

The object of the contract must be legally tradable. It can be individually specified or specified by type. It is also permissible to agree on the purchase of a future object—one that does not yet exist but will come into existence. The object can even be a third party’s property. The sale of someone else’s property binds the contracting parties. However, if the buyer was unaware and had no obligation to know that the object belonged to someone else, they may withdraw from the contract if this prevents them from achieving its intended purpose and may claim damages.²⁰⁸