You want a dash camera with parking mode so you can finally catch whoever keeps dinging your bumper in the parking lot. It watches your car while you sleep, which means you need a hardwire kit installed so it doesn't drain the battery. Most setups run about $250 once you factor in the camera, memory card, and wiring.
The best time to buy is during major retail sales events like Black Friday or Prime Day when these units actually drop in price. Do not wait for a special financing offer to negotiate the price of the gear itself. You want the lowest cash price first, and then you figure out how to pay for it.
Remember that the 15-month intro window is a hard deadline, not free money. If you still have a balance left on the card when those 15 months are up, the standard interest rate kicks in on whatever is left over.