I have used the Internet marketplace known as eBay for many purchases over the years, but I recently engaged in a different (for me) form of e-commerce: buying used automobile parts. My son's 1991 Toyota Corolla experienced a small engine fire recently after he and his brother rigged up a battery mounting device consisting of a pair of metal coat hangers, which inevitably made contact with the battery posts and shorted against the hood of the car.
Anyways, the resulting sparking caused some wiring to catch fire, and he spent a few hundred dollars replacing the battery, electrical wires, and the coolant fan. However, the repair shop could not find a coolant overflow jug around town, even a used one, so the mechanic plugged the radiator and advised us to search online.
Sure enough, a vendor on eBay from New Orleans Louisiana listed a used coolant overflow receptacle for a mere $21, less than a third of the price of a new jug. A few days later and the grimy-but-serviceable part arrived in the mail, and the car will now be ready for the hottest summer days with its new-to-you overflow container.