Hi Babette,
There are a few large (international) Internet dealers (Bax, Thomann, Keymusic, Gear4music) on the keyboard market in the Netherlands. When someone in the Netherlands googles on the desired keyboard, you will automatically find those dealers advertising (incl. German / Belgian dealers). That also includes the prices of the desired keyboards. For the SX900 it currently fluctuates between € 2156 - € 2356. There are of course plenty of local dealers, who are also making good progress (Oostendorp, Joh.de Heer, MuziekhuisDera, etc.) The large internet dealers (usually) do not trade in and sell through their internet shop. The (smaller) local dealers often offer more / different service and you logically pay for it. The negotiation margin is not large for the SX900, at most a few hundred euros? This is because every advertiser wants to put down his lowest price on the internet. It is more difficult with an evt. in return. Many dealers would rather not trade in 'old' PSRs, because there is not much to be gained from that. Or you will receive very little in return. Ultimately, it is a one-to-one negotiation with your dealer. It just depends on what you choose, what appeals to you and what you have left for it.