Sell a laptop / Acer Predator Helios 300?

Because I want to buy a new PC, I want to sell my old gaming laptop. For how much can I resell it? He's not quite two years old.

That's him:

https://geizhals.at/acer-predator-helios-300-ph317-52-7470-schwarz-nh-q3dev-009-a2055792.html

Have a look what similar notebooks cost at E-Bay or E-Bay Classifieds.

An I7 with GTX 1060 16GB RAM and 256GB SSD is not such an unusual configuration that you can't find it there.

https://www.ebay-kleinanzeigen.de/s-notebooks/gtx-1060-notebook/k0c278

What I see around 650-700, - €

I've already looked at Willhaben there they cost around 900 euro