I did a google search for 2006 Monaco Knight and you should too. Then take the comparisons to your dealer and see what they say.
It seems from what I see they are into serious lowball offers, and you should take the time to try and sell it yourself, or consign it perhaps.
If you have to move on, then figure out what you need from it and get what you want now. They are a good make, and the depreciation is mostly gone. You might even begin to think that even though it costs to maintain, you pull a new fifth away and it drops 25% the first year, and it is hard to sell too.