The NX documentation is quite clear about what goes into the library or not, see paragraph 5.
You would have to change the Tcl scripts and database file to be able to export and retrieve the catalog information, see creating new classes for further information on customizing the tool library. In addition you may want to also check what you have to do to get these changes migrated into a new release, see the NX documentation.
From my experience, I would start with using the tool library without any customization. You will never succeed if you try to get all bells and whistles in the first step.
The NX tool library is not meant to contain information that is needed to buy the tools, this is usually stored within an ERP system. Using a unique library reference will allow to build a connection to the tool record in the ERP system.