It's really difficult to pin a value on something like that without holding it in your hands. Omega actions are quite simple so taking care of a broken trigger shouldn't be too big of a deal. But a rusty bore is a rusty bore. For me, that puts the gun at about 20% of it's original selling price, even less with the broken trigger.
But it sure would be interesting to pick it up for a song and have it re-bored to .54 or .58 caliber with deep rifling and a slow twist for round balls.