If you're looking for a free solution to convert DBX to PST format, you can try an easy manual trick. Though the manual trick doesn't convert DBX files into PST format, but you can migrate from Outlook Express to Outlook with ease. The manual trick doesn't require any paid software or any other cost. You just need to use Windows Live Mail application, that's it. Windows Live Mail application has both Import and Export features which help you import email messages from Outlook Express client and export them to Outlook client. If you don't know how to do that, you can take help of this blog post:- http://migrateemails.com/2015/07/30/convert-dbx-to-pst/