Interested in one of these as well, although after a Natural Gas one.

Anything 9KG is LPG.   Small camping / hiking stoves use butane.

Caravan / RV supply shops usually sell them. 

Regular gas detectors can´t be run on anything but large 12V car batteries. They use too much power.

Check here: https://www.gasdetectors.co.nz/portable-gas-detectors/ 

jarledb:

Regular gas detectors can´t be run on anything but large 12V car batteries. They use too much power.

 

Do you mean a Carbon Monoxide alarm?

lxsw20:

 

Do you mean a Carbon Monoxide alarm?

 

Carbon monoxide comes from incomplete combustion, e.g. mis-adjusted or poorly ventilated burners.

OP is looking for gas leak detectors, which detect leaks that could lead to explosions.

Sorry to post on such an old thread.

Did anyone here manage to find an LPG alarm?
I'm trying to find one myself...

I came across this one in Bunnings but it's $111!
bunnings-fireangel-natural-gas-alarm

There is also the Xiaomi "smart" option which can be found for around $35 on aliexpress
Xiaomi-mijia-honeywell-smoke-and-gas-detector
although I'm not sure I would trust it to be reliable enough for an alarm.