The purchase or contract for any supplies, material, equipment, or contractual service by any county office, department or agency, or the sale of surplus, obsolete, or unusable supplies, material, or equipment by any county office, department or agency contrary to sections 375.72 to 375.76 is voidable. The head of the office, department or agency is personally liable for the cost of such an order or contract and for the reasonable value of supplies, material, or equipment sold. If an order or contract has been paid for out of county funds, the amount may be recovered in the name of the county in an action brought for that purpose. Property sold contrary to sections 375.72 to 375.76, or the reasonable value of the property, may be recovered in the name of the county in a similar manner.