Depends,
Geographic location and available market make a difference, in the US they are fairly desirable and a lot of population creates more of a demand.
They are not rare, but if actually NIB (unassembled and original packing grease on it) not As-NIB (original packing grease gone, no marks whatsoever) will make a paying diff to a hard core collector, the rest of us hunters ??
Seeing how in Canada we are mostly pump and auto guys especially west of southern Ont. with a much lesser amount of smallbore SxS upland purists and both 12 and 20 guage BSS's are way heavy compared to most all other similar game guns( sold a 12 earlier this year because it was just too hefty to lug all day in the bush). What you see them asked for in the US will usually have you sitting on it for a long long time here.
See lots on the US market asked prices from 1,200 to 1,600, but I doubt they actually realize those kind of prices. Personally, my top best offer if condition is as you say, would be 1,200 Can.