Smart 451 Market Value

Good morning, temporarily I played with the idea of replacing my Smart 451 for a new car. I noticed that the dealer prices do not reflect the vehicle value seizing. I am aware that the dealer with the used car has some work and must give guarantee, but the offered purchase prices, which were between 1400 € and 270€, I find already questionable. What is your assessment of the market value of the vehicle? The usual used car exchanges only reflect the desired prices, which are probably corrected downwards when selling. My vehicle: Smart 451 MHD 71PS Color: CC2L warm grey Number of previous owners: 1 Built: 10/2011 Running power: 90000km Equipment: Pulse Special equipment: Power steering and the rare hands-free device, which can be seen next to the speedometer as LCD clock. Thank you for your feedback. Roman