Let me translate that into car terms.
"LXP gasoline 1000 horsepower" car. Super cheap!
Would you believe that sales pitch? No? Ok then. 850 lumens OTF output is tough to make without careful design. In general:
Distrust anything with its product type as the name. "MP3 Player 4GB" from "MP3 Player, inc" is unlikely to have high quality or good design. Similarly, "[Battery size] [suspiciously-round output number] flashlight" is unlikely to be very trustworthy. Heck, if I released a series of flashlight called the Lumen, and then started naming them "1 Lumen," pretty soon I would have the "10,000 Lumen." Does that mean it's output? Nope. Similarly, lots of crap-bay lights have "W" as a part number. So "5W" doesn't mean 5 watts.
In short: There are lots of ways you can spend the euro better. Heck, try out a Sirius Osram flashlight and let us know how they are. I'm resisting buying one, but they look SO nice.