Govee RGBWW Smart Light Bulbs, Colour Changing, 4 Packs - Sold By Govee UK FBA

Cheapest according to Camelcamel and Keepa (see comments below)

16 Million DIY Colours: Govee smart light bulbs own millions of colour and 54 preset scene modes, you can explore your favoured one or pick one suits your Christmas mood most, bringing yourself a real fantastic lighting experience.
Music Sync: Our smart light bulbs change colour and brightness simultaneously when sounds are detected by the microphone on your phone. (Note: only works when the microphone is not occupied. Download Govee Home App and enable microphone permissions.)
Smart Control: Govee colour changing light bulbs make it possible to control your bulbs with simple voice commands. And you'd also feel free to turn your smart light bulbs on/off, adjust brightness, or change the colours, set scenes via Govee Home App.
Group Control: Wanna manipulate your smart light bulbs and other Govee smart products at the same time? Just need to set scheme and and add them in, then they can be controlled together(please connect you bulbs with stable 2.4Ghz WiFi).
Timer and Schedule: Applying the smart light bulbs to your daily routine now is easier than ever, with timer function and modes like Sunrise & Sunset, you can set your bulbs to brighten when you wake up, and gradually dim when you fall asleep.