I can't reply to the existing thread below as it is too old, but I thought I would share that I also broke a batten in my 5M wing, and I just received some replacement items that look just like the OEM item but were only $3 each. From playing with both an original and the aftermarket item they appear to have similar weight and flex profile also, but I am yet to use them in my wing.
I ordered 4.1mm battens from www.permex.com.au/pultruded_fibreglass_rod.htm
www.seabreeze.com.au/forums/Stand-Up-Paddle/Foiling/Duotone-foil-wing-5m-broken-batten?page=1