A friend has asked me to get a value for his Volta 1/4 hr repeater. It's in a gunmetal case, it runs and everything works as it should. I see the minute hand is badly bent, but that shouldn't affect the value much. It appears to have 13 jewels.
I sold at auction a fully working Volta chronograph/minute repeater in a gold case a few months ago. The watch was older than yours, dating to about 1898. It sold for $2,000 which was about $800 over gold melt value.
The two watches share little more than the name in common, and I would suggest that mine was of greater value than yours being a minute repeater and a chronograph. But I hope this may give you an idea of the value of the Volta name.
I suspect that's high. I think the market would expect a repeater to be in a precious metal case, a minute repeater carries a premium against a quarter, and mine was older than yours (which I would expect to command a premium). So unless yours is a rare or unusual movement or repeater, I would have put a price on your movement of $300 as against mine at $800.
However, since much of the value is simply a matter of current fashion, that figure could be way out. What you have is probably so rarely seen, let alone sold, that there has to be a lot of guesswork involved. I know that's a cop-out, but it's true!
Just for your interest, photos of my ex-watch are below.
They actually had a very high reputation in their day. Volta was the brand name of Maurice Ditisheim, an excellent and inventive watchmaker, and the firm was taken over by his son Paul who created the brand name Solvil and was (I think) one of the early makers of thin watches.