Valgine is not a company I'm familiar with. I've seen their dive watches go for a few hundred on eBay. The vintage stuff usually under $100 but it depends on condition. I believe Valgine used 3rd-party movements so when the guts are the same it mostly comes down to if the brand is popular. But it also means it could be easy to get serviced if you wanted it cleaned up.

Opening up the pocket watch to see the movement may be the only way to identify it. I'm not familiar with the market on pocket watches.

Ah yes I read Waltham pocket watches are collectable. I got a set of vintage wrist watches to try and bring back to life and one is a Waltham (after they went Swiss though).