While USB SDR receivers that include 303Mhz support are easy and cheap to find, transmitters are both harder to find and more expensive. It almost seems like you’re looking at the hackrf which is $300USD+. Probably the most fun and flexible, but harder to justify. The YARD stick one may also work for this, at ~$150USD? I’d need to figure out a case though.
The really cheap “303Mhz” radio / transmitter pairs you can find online aren’t true SDR, and only let you send signals between the pair.
Any other solutions out there? I have pretty limited hardware / radio hacking experience, and I keep feeling like I’m missing something obvious here.
Don’t know if you’re still working on this, but I found another thread while searching for the same info. Might be useful for you. To the best of my understanding Hampton Bay remotes are made by the same company that makes Minka Aire’s. Hampton Bay Fan RF/MQTT bridge
Note that a good chunk of that $150 USD for the Yard Stick One might be because an antenna is included. I was able to find one closer to $100, without an antenna (I had a 433mhz antenna that works well enough).
I wanted to learn this anyway and had time over the holidays to play around. So I convinced myself the initial investment was worth it Pretty cool project actually.
EDIT: It was Adafruit that I ordered a Yard Stick One for about $100, without antenna.
I’ve been looking into this myself and gotten a little discouraged since I’m not really feeling like spending $150 for the Yard Stick One right now. Looking into it more, it seems this may be doable with ESP8266 and a radio chip you can get for ~$2USD on AlliExpress.
To help with the cost of the Yard Stick One, you can skip the antenna if you already have one. I purchased mine for $99 without since I already had the right antenna. I realize $99 is still a lot for essentially a remote control, but I use mine for other projects other than my Minka fan control