University costs, Testbooks

I am currently in my third and final year of univeristy and i have just been hit with some textbook expenses. I am sutdying environmental science so that i can bring clean and cheaper energy to rural communities within Australia. I am currently on government benefits and have not been able to find a part timejob as i am at uni 5 days a week and volunteer on the weekends. My mum is a single mum and is currently supporting my elderly grandmother and definately cannot afford these books nor do i want to put the burden on her. Any kind of help would be greatly appreciated and even if you can't help thank you any way.