Wow, that's a lot of money!
I googled this person (no less that 277,000 hits), and he is apparently a very, very well known scammer, that keeps reappearing under different names. He starts a new account, then makes a lot of purchases to get good feedback, and so can better catch people off guard when he starts selling.
His feedback already raises a red flag IMO, too many negative comments related to plants not arriving or not what they were sold as.
And according to a german forum a case has been filed against him, and victims should contact the prosecutor in charge of his case. But don't know if people outside of Germany can do that.
Ermittlungsverfahren gegen Kai Najda