The only step-by-step guide to adding pricing information that I know of is Eric Wilk's book ArchiCAD - From CAD to Quantity Survey listed here:
http://www.boutique-fc-cadlink.com/
The process is not possible with the 'interactive schedules' - you cannot add computation fields to them. Instead, it is done via 'list schemes' and creating 'property objects' and database entries. These things are part of the 'old' Calculate Menu, which is not displayed in the default AC work environment any longer - you have to go into Options > Work Environment to bring all of the related commands back into the interface.
An alternative to doing all of the computation in ArchiCAD is to publish the schedule data as text files (CSV) and to link those text files into an external spreadsheet or database program.
Sorry to not provide a specific answer...
Karl
One of the forum moderators
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB