Aahahahahahahahahahahaha !!!! The acclaimed artists, who are on some of the biggest air fairs, in big galleries, who are often even working in academia and produce original and strong work can't get those prices on any market.
A piece of a large piece of that size, that can have only decorational purpose is at best 2k, just covering the material and the shipping he would have to handle for you. Smaller piece, if you feel generous 300-400 euros. Let's say his work can have some value, and that is decorational value. Ends there.
But hey guys if you are so stupid to want and change DMs with 'him' or his wife likely, and think he's talking to you. Sure pay him lol