What is the ruling on purchasing foodstuffs distributed as charity by organizations, and what is the ruling on someone who sells what was given to them from these materials?

It is permissible for the owner of assistance to sell it, unless the donating entity stipulated that it should not be sold. If they stipulated that, then it is not permissible to sell it except with their permission. As for merchants buying these charitable items at a meager price, that is an inappropriate act. There is no sin on the buyer for bargaining with the seller at any price, as long as the seller is an adult of sound mind, for what is forbidden is deception, fraud, and misleading the ignorant. There is no prescribed Sharia limit for profit in trade, except in the case of selling to an ignorant person who does not know the prices, in which case it is not permissible to deceive him and sell to him for more than the market price. Consequently, there is no sin in buying a commodity for less than its value as long as the seller is aware of the market and not ignorant of it.