Can I Purchase Only The Pulley Or Hub As I Don't Require The Full Kit?

Yes. These items can be purchased seperately.

- The hub can be found here:

http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/PLY601 

- Individual pulleys can be found here (all pulleys are the same price regardless of size):

http://www.maceengineering.com.au/epages/shop.sf/en_AU/?ObjectPath=/Shops/mace/Products/PLY000/SubProducts/PLY613