Hi Dave,
Pinion wire for watches is not easy to find these days. This company can make stuff to order but I would imagine its expensive 
http://www.rushgears.com/
They have a PDF but I am not sure if it is saying the pinion wire is 24 leaves?
http://www.rushgears.com/catpages/pinionwire.pdf
I think your best bet is to look for a donor movement, if that cant be done your only other option is to look at getting set up for cutting your own.
Sorry I cant be more help.
Paul.
