In my experience the limited editions / wildlife special editions / ducks unlimited editions ...etc ....add very little value, if any, to the value of a shotgun. $ 1,100 is way too much for this gun / even unfired and new in box.
The value is akin to the same model of 870 / that is new in the box today - with the same stock, barrel and chamber length dimensions. There are a lot of 870's out there - but even the 870 Wingmaster these days, new in the box, which is the top of the line 870 sells new for around $ 600.
It might be a cool gun to own / but don't pay more than you would for any other new 870 ...or maybe bump it $ 50 for the engraving / or writing on the gun / or the waterfowl scenes or whatever ...but no more than that.
If the seller is asking for $ 1,100 for it ...he'll be asking a long time. These guns are auctioned off at charity events, given as gifts sometimes - but they don't retain their value / and part of it is some guys don't want to shoot a gun with this kind of engraving and stuff all over it. In my area - we see quite a few of the "ducks unlimited special editions for sale" ...and most of them sit for a long time ... But just my opinion remember...
Don't buy it as an investment ...because it will not appreciate much - if at all.