Bucherer used quality movements in their watches (fully jeweled), but as a collectible the brand itself is not sought after. Therefore, I would put the value about the same as any ordinary (but well-made) watch with similar features and construction. Think vintage Wittnauer, Zodiac, etc.
The model number will neither clarify the value, nor indicate which crown to buy. Your watchmaker should be able to find a replacement crown based on the movement (guessing A. Schild) or by measuring the stem and tube.
If the composition of the case is gold-filled or some base metal (in other words not solid gold) then I might pass the watch on to someone who may have an interest in repairing it themselves. The repair/service would likely exceed the value of a gold-filled or base metal watch.
A solid gold watch would have greater value based just on the value of the gold content, but I think we are not allowed to offer valuations on this forum.
Edit: the case back looks like white metal, like steel? Hard to tell from the photos. If the watch has a steel back, personally I would pay it forward to someone who would benefit from the experience in repairing it, or benefit from the sale of it as-is (charity).