You have a lower grade Victor Sarasqueta gun, commonly called a "boxlock" action. I suspect the $1,500-$2,000 guns you saw are higher grade "sidelock" action designs. They certainly should be at those prices. Look again at the proof marks, you should see a single digit letter followed by a single digit number, such as F1, which means the gun was proofed in 1960, G1 means 1961, H1 means 1962, etc.
Given that it's a 12 gauge, it appears to be in good condition, my guess would be $600-$800 at retail.
VS made both entry level guns, which is about what you have, and higher grade guns, such as the sidelock designs mentioned. They are usually well made guns. They were known as "The Gunmaker To The Kings", the kings of Spain that is. The Spanish kings liked and used their higher grade sidelock design guns.
