Try Jay Glaser, he should be able to help match your old battens.

http://www.glasersails.com/catsails.htm

They stock fiberfoam battens.

If your battens are less than 14-15 years old, they are probably fiberfoam. Sometime around 1997, Fiberfoam became the only company that I could find that made foamcore battens. I remember very well having to pay shipping for a 11 foot long package from Austria.T