$2k is absurd for a 28-2, but it's also not 2015 anymore, and finding a nice 4" gun for $600 would be a steal.
Value can vary significantly, with the highest being early S serial numbers, decreasing the newer the gun gets. 4" worth more than 6". These guns were working guns, and most were used for their designed purpose and show it. A pristine gun in near unfired condition will bring a significant premium, especially with original stocks, box and papers. Early HPs ('pre-28') will also bring a premium.
I would not be surprised to see a 4" early S numbered gun in high condition go for over $1k, but a late 6" gun with typical wear could go for $650 or so. Big, sliding scale in-between....