The Smart Plugs from Ledvance or formerly Osram are long-running. I stocked up on them years ago and they are still very satisfied with their work. The 4-pack is now on offer at iBOOD.
4 Ledvance Smart + Plugs for € 30.90 at iBOOD
If you are looking for a few smart plugs, you should stop by iBOOD. There is the 4-pack on offer for € 24.95. The deal price comes about because there are another € 5.95 shipping costs. Mathematically, you get a total of € 7.73 per connector.
By the way, they can be integrated into the Philips Hue Bride (no HomeKit possible) or into an Echo with a ZigBee Hub.
Here’s a little video from me, in which you can see the most common smart plugs in comparison.
If you want to exchange ideas on the topic, have a look at our “Smart lighting group”On Facebook. There you will find a huge community with whom you can exchange ideas on the topic!