Some of these items are available individually on PlayStation Network There is also a long list of promotional content which is no longer available, or only available by purchasing the collectors edition.
MASS EFFECT TRILOGY PS3 DLC CODE
It is likely that all of the content that 'Requires access to Cerberus Network' would be available with any copy of the game which includes a Cerberus network access code (which is included with the PS3 release of Mass Effect 2).
It looks like the Mass Effect Trilogy contains the following games