A good multi-pack of indoor security cameras keeps an eye on the main entryways, the living room, and the back door all at once. You want something that lasts a few solid years so you only buy this setup once instead of replacing glitchy hardware every season.
Major online shopping events are the sweet spot for these. Wait for the big price drops, and keep an eye on last year's camera models because they usually get deep discounts while keeping the exact same video quality and app features you actually need.
That 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 you owe.