He probably has one of the 1st generations which were cheaper (and crappier). I would not recommend paying more than 100EUR for it. The build quality was terrible and the firmware ridiculously buggy. I am told both things have improved in recent GPD endeavours but then so has the price.

OP here – I got it second-hand, from a guy who ordered it directly from GPD as a note-taking device but it didn’t work out for him.