As we head into 2025, there aren’t many things preventing homeowners from building out a basic home security system. You can start small and cheap with the battery-powered Blink Outdoor 4. If you don’t mind that they’re refurbished (with the same one-year warranty as the new models), you can get two of them with a Sync Module 2 for $74.99 ($90 off) at Amazon, which is only $10 more than the all-time low. A single Blink Outdoor 4 retails for $99.99 new...