I want to list this beauty on Gunbroker, but need more specifics because it could be worth a lot and it's not my area of expertise.  It's a model 1884 US Springfield Trapdoor Carbine in 45-70. Gun is in incredible shape given it's age, which makes me wonder if it's been refinished.  Lock work is color case hardened.  Barrel length is 22". A few minor scratches and specs of rust, but overall in great shape.  Bore looks nice and shiny, maybe a few specs of surface rust (need to find my bore light).  Serial number is 452992, which puts the gun's DOM around June or July of 1889. 

The below website shows this gun valued at $900-$2400; does that seem accurate? My thought was to start the auction at the lower end, because the guns value is really what someone is willing to pay for it, and the auction would hopefully take me there.

What details/pics about this gun should I focus on in my auction listing? Do you think it has been refinished?

TrapDoor Collector Website

sure that isnt a repro? that looks like a repro

It has either been refinished or it is a reproduction . The case colors look strange . The wood is too nice and the blue is too deep polished .

First of all I think you meant Carbine and not Cadet.  
Most defiantly has been refinished.  As said previously the stock is shiny and appears to have been sanded.  That is not original color case hardening.  
If the bore is good then it would be worth $700-900 as a shooter.  
The problem is people that want carbines will want an original condition carbine, even if the condition is a little rougher or has more patina to it.  Depending on the bore, it would be considered a shooter grade.  Since it has been refinished it is almost in the same price category as a reproduction, with the reproduction having a little more desirability as a shooter because of the newer and stronger metal.

Yes, I meant Carbine, not sure how I screwed that up. I updated the original post.

No evidence of a repro, so it sounds like the consensus is what I suspected: it's been refinished, thus hurting value.

Someone did spot heating and quenching with a torch.

If that's not a repro it's a damned shame.