You won’t find Zigbee or Z-Wave TRVs for £10. If you do, let me know because I want them too!
You won’t find battery operated WiFi ones, because WiFi is too thirsty.
I’ve never looked for Bluetooth ones, but their range may be an issue.
No idea about 433Mhz.
For £10 you might just be able to buy a single wired dumb electrical radiator actuator, but then you’ve got to add the smarts yourself. And it’s not battery.