Tyre TPMS broken

[akkers5]

I had a puncture and took the car to a tyre place. The guy took the wheel off and took it inside only to come back with a broken sensor in his hand. He said that the sensor was broken when he opened the tyre. I think he broke it when opening the tyre. All sensors were working and there were no failure warnings as I drove there. But hey up.
Anyway I came back home with a repaired tyre but no sensor; I keep getting sensor failure messages now.

So, apart from buying a genuine BMW sensor, are there any other options? Do after-market sensors work? And more crucially how do you register a new sensor as I cannot see an option for that.

[QuartzDad]

I've bought sensors from eBay and they worked fine.

Registration was driving for ~10 minutes until they were recognised.