What is the legal ruling on selling goods of the same type at different prices and distributing them by lottery among willing buyers?

For a sale to be valid, the price must be known at the time of the contract. This is due to the Prophet’s — peace and blessings be upon him — prohibition of gharar (ambiguity), which is ignorance and risk leading to dispute. If the sale is conducted by lottery, where the price of the specific item is not known before the lottery is drawn, this invalidates the sale. This is because it is a sale of something for an unknown price. The fact that the buyer knows the displayed prices is not taken into consideration; what matters is the knowledge of the price of the specific item he is purchasing. Nor is mutual consent relied upon in such cases, because Islamic law has prohibited certain types of jahalah (ignorance) sales, even if there is mutual consent, such as bay' al-mulamasah (touch sale), al-munabadhah (throw sale), and al-hasah (pebble sale), due to the gharar (ambiguity), ignorance, and conditioning of the sale involved therein.