Dear Namwob (if I may be so familiar):
It doesn't look like a very unusual Strombergshyttan, so you could get an an idea of the low end of what it might fetch by searching Stromberg in completed eBay auctions and looking for vases of a similar size and level of engraving. The smaller engraved pieces tend to fetch surprisingly little. I think it's more likely to be early 50's than 20's. For example, there a similarly shaped vase with deer on it, rather than birds, that was designed in 1954, and is marked B 489. (B is used for vase by the company.)
David