As already mentioned, Aramberri was one of the lesser known Spanish manufacturer. Like other gunmakers over there they built shotguns based on market specifics and their products ranged from ordinary to good quality. As is the case with many (but not all) Spanish brands in terms of how the product is evaluated - it is the gun and not the maker.
I'm afraid the older Basque guns provided that year of make is correct won't fetch much more specifically if it isn't one of the prominent brands. Therefore, ball park figure, depending on the overall quality/configuration of the shotgun it may be anywhere from $200 to $300.
If memory serves, Tradeex (Dealer) had/has? some a while back in various conditions.