You've actually got a couple of different ways into the Tradfri ecosystem. In addition to the $80 starter kit on the bottom there, you could also try a $20 wireless dimming bundle (top right) or a $25 bulb-and-motion-sensor bundle (top left).
The main $80 bundle comes with two bulbs, a gateway hub to let you control things on your phone and this wireless remote for dimming things up and down.
The bulbs in that $80 kit are nice and bright, clocking in at well over 900 lumens at their default setting -- noticeably brighter than a 60W incandescent. They also offer three distinct color temperature settings that you can switch between in the app.
The $20 dimming kit comes with a single, fixed color temperature smart bulb and a wireless dimming knob. There's no gateway hub here -- you'll pair the knob directly with the bulb and skip the app altogether.
The knob features two separate halves that sit together magnetically. Twist the yellow part to turn your lights on and off or dim them up and down. Each knob can control up to 10 bulbs.
When the motion detector detects motion, it will turn the bulbs it's paired with on (again, up to 10 of them). You can turn a dial on the back to adjust how long without motion before it turns the lights back off.
