Here's a thread with some good discussion on these insignia. They are reproduced and the reproductions are of good quality. I don't know about the example you posted but this thread may be of a little help in deciding.
Supposed HJ firefighting brigade cloth armpatch
Thank you for the help, it seems too risky to me as the quality, as you stated, is very good of the reproductions. I think I will save the $50 and pass on this one.
I have one of these 'firebrigade' patches, and a German Workers' Party (DAP) pin that I am making available. Should someone be interested, please let me know with a fair amount. These are both authentic, directly from my grandfather, who I have other items from.
I know it is an old thread but figured I would post my similar patch with German news paper. All the examples I have seen on the net have variances. One thing I find typical of the examples I have seen online are the length and thickness of the white thread bordering the flames. These two have longer borders than other examples I found. The paper on mine seems to be old as I was having a hard time translating the words I could see. The only thing to glow under a black light were spots of glue. If it is a fake someone did a good job producing it.
I should have added to my previous post that all the online examples I see of this type are very consistant in design and folded.