I buy old photos at flee markets and on auction websites online like Ebay and the Swedish site Tradera. This picture I bought online. A very handsome young man I’d say. C Löwenhjelm. Photo by Lundmarks Atelier (photo studio) in Umeå.
At the Swedish Genealogy Society there is a database where you can upload pictures like the one above. I know they are rebuildning the database, it is more than ten years old and have limited search abilities but it contains 129196 photos at the moment. If you want to check it out it is found at http://www.genealogi.se/portratt/form.php . You are able to browse first on an area in Sweden and then a photographer / photo studio or do a search.
This particular photo I uploaded in 2009 and only a few days later there was a comment on who the person might be in the Swedish 1900 census. http://www.genealogi.se/portratt/comment.php?id=95375