Each seller of a product is willing to sell as long as the price he or she can receive is greater than the opportunity cost of producing the product.

Sellers are willing to sell a product as long as the price they receive is greater than the opportunity cost of producing it, because this ensures they are covering their costs and potentially making a profit. Opportunity cost represents the value of the best alternative use of resources, so receiving a price higher than this cost means the seller is making a rational economic decision.