@mkprofiles said:
I am going to bump this as I am still looking for help
Not totally sure of everything you are after, but won't the facility of custom fields in Dynamic components introduced in V7 be of use.
I am no coder, and have not studied all the possibilities in the formulas that can be used in the 'Custom' fields, but if I read your examples correctly, you should be able to add items based on calculations (eg length pricing).
I had a similar requirement for adding custom attributes and found that the cost of the options available previously was prohibitive, but a breeze in V7 (except for the reporting - but that's the subject of another post http://www.sketchucation.com/forums/scf/viewtopic.php?f=180&t=15052)