> Saxon Professional or Enterprise Edition are available without cost to non-commercials opensource projetcs?  
No, sorry, they are only available on commercial terms.
If you need the functionality of an extension such as saxon:line-number in an open-source application project, you can usually implement an equivalent as part of the application. Saxon-HE doesn't allow dynamic linking of extension functions loaded from the classpath, but it does allow "integrated extension functions" that are explicitly supplied by the application.
Information is here:


Michael Kay