Update: I've recently found information on this gun. It seems to be a 1914 Retolaza "Eibar" 7.65mm. however I cannot find anything reliable to determine its value. Can anyone offer suggestions? Thank you.
Years ago I bought one from a guy I worked with. His uncle was a veteran who got from a captured Italian officer during WW2. It was in great condition with the original holster. The pistol pictured here has led a rough life.... This one would need a lot of refinish work to bring it back to presentable condition but it will never be worth more than $200 - $250. My .32 ACP was a decent shooter but I traded it off long ago. Your pistol might fetch $150 on a good day to the right buyer as it is.
One should read up on the makers of the Ruby; it is a great and interesting bit of firearms history.
The pistols are typically rough, crude having bad triggers and worse (toss up) sights and a fairly short service life. However they went bang on schedule (until they didn't) and quite inexpensive. Of manufacturers, there are between seventeen and sixty thousand 'companies'. It was pretty much a cottage industry of the Basque people of the Iberian Peninsula where it joins to the mainland - the Pyrenees mountains, the country of Andorra. That myriad of 'small companies' eventually formed the Corporations of Astra, Star and Llama. Those are all defect now due to lack of funds, but I'm way afield.
Those pistols are not particularly valuable, but they do prove what is possible with limited machinery. Much more than a zip gun.