Question on the selling price

Hello to all who know each other. I bought myself a Yamaha Mayestik 125 scooter. The scooter is year 2005 and had the last time TÜV 2011. The owner (a good friend) drove with the scooter only 630 km then he stood dry for years and in front of the sun safely in a room.The thing is like from the shop and as good as not yet entered. I know standing around is also not so good. I wanted to keep it myself, but it turned out differently. Battery all the flow I will still do this. Now to my own question for how much could I offer it on the sales platforms or what would be a reasonable selling price.