I just got a full-battened main too without battens. You can order them online from Sailrite
and probably others. With your main you have some long battens so add up all you need and it will come rolled up and you can cut them to fit. Here is what they say for 1 5/16 though you may need a wider one:
Batten Pultruded Material 1-5/16" is a durable, lightweight and inexpensive pultruded non-tapered fiberglass
reinforced batten. This batten is completely adequate for the most demanding sail applications. It is easily cut with a hacksaw and can be sanded to provide for variable flexibility.
Width: 1-5/16 inch
Thickness: 1/8 inch
Maximum length: 22 feet
Pultruded Batten Features:
Easy to cut with a hacksaw
Sold per foot (full feet only). Lengths greater than 8 ft (96 inches) will arrive coiled, please use caution when unpacking as they are under a great deal of pressure.
is between $4 and $5 per foot.
If you can't get those, I am not sure. I have heard of other things being used in a pinch but you can probably imagine those are NOT preferrable..(bamboo? PVC pipe?)