Since they were melted, there is no way to determine the actual value, beyond the gold. So sure, they were worth $50K...
If they were worth that much as coins they wouldn’t have melted them. It’s not that tough to get things appraised, and the reality is unless the coins are of a type that has an active collecting community (which generally requires a good level of rarity) they usually aren’t worth more than the metal in them.