Also that router is currently on sell on JD.COM (https://item.jd.com/100017450204.html) priced at ¥599.00, about 80€ I guess.
There are rumors says Xiao Mi has somewhat subsidized their line ups with intention to create their own ecosystem. If true, that's one of the reason why their devices can have such low price.
On the other hand, ¥599 is not exactly cheap in China. Somebody can literally survive a entire month on that amount of money. A "normal" price for a "regular" router is around ¥70~¥200.