Section 28. A seller may recover the fair market value of goods, wares or merchandise sold, if they were, for the purpose of the sale, weighed or measured upon weighing or measuring devices not sealed according to law, or weighed or measured by a person not a sworn weigher, measurer or surveyor, or by a person not authorized by law to weigh or measure the same, if such sale is made in good faith and the purchaser is not injured thereby.