Radio Modules

[Dave21w]

For anyone in the UK these people have some great prices on radio modules for home built stuff

https://www.rfsolutions.co.uk/

You may also want to take a look at the devices these people make, not sure how easy they would be to get though, their product page shows some great modules and single chip transmitter / encoders with minimal component count.

https://www.hoperf.com/