Thanks for the replies. It seemed a pretty steep expense for parts commensurate with the quality/value of the bike.

I'm completely ignorant regarding cable compatibility with derailleurs, do I need to look for anything specific to match a cable to my Huret Duo? Usually I research extensively before making a move so I actually understand what my options are and learn something (and mostly buy online), but this time I made a rare exception and just trusted the discretion of a sight unseen salesman ... not something I ever really do in NYC and obviously a mistake (never again!). Gah.