It is not a Seamaster, and not a Constellation...
I believe it is a vintage Omega De Ville
I believe I have seen them go as high as $500-600 but in that condition more like $150-200, but that is from eBay... I look at vintage Omega's a lot and usually sort by costs and there are quite a few in that $240-300 range but usually have slightly nicer dial... that bracelet is cool though...