last year we (293) had kevlar bin herding arms. They were very very strong and weighed next to nothing. 2 years ago we had a spinning drum on our bot that would shoot the balls up into the air and into the goals which was made of fiberglass. I've have always used
http://www.cstsales.com/ for composites and they have good prices. If you only need a little bit than car body repair kits are great. They come with epoxy, hardener, and cloth and their great to learn with. They're about 20 dollars and you can find them at most auto parts stores.
Ben Van Selous