You will not be able to purchase the basic version of COMAP, as the VPI (Verband der Güterwagenhersteller in Deutschland e.V) is providing it. Every company, which purchases the VPI guidelines, receives free access to their own basic instance of COMAP.
Due to the limited functionality, the basic version is more designed for a productive use in companies with a small fleet of wagons respectively for small maintenance workshops. Companies with a large- or medium-sized fleet as well as larger maintenance workshops can use the basic version of COMAP for testing the digital data exchange according to VPI 08 in their system or with the ones of their customers or suppliers.
Information regarding the professional version of COMAP can be found here.