I've got wood

Think you could make polo mallets shafts? We've used wood and bamboo before, but they break quite quickly (although so do ski poles a lot of the time)...

Potentially. I know little about polo though so I'm not sure of what's required weight/flexibility/strength wise.
Any suggestions?

I must admit the butt end of split cane fishing rods always looked perfect to me - cork handle, strong and flexible.