A pretty great deal if you like the Batiste Dry Shampoo brand! I use it every few days, helps extend the freshness in your hair without having to wash it. Also leaves your hair smelling pretty good.
Works out to be only if you're an eBay Plus Member otherwise postage is $8.95.
6pk Batiste Dry Shampoo 400ml Hair Care XXL Volume: $4.92 per bottle / $1.23 per 100ml
One bottle of this exact Dry Shampoo is sold on Catch for $17.00 per bottle!
If you're looking for another alternative, you can try Targets brand 'Girlz Only' which is reasonably priced all round. They also have a range for Blondes, Brunettes & a No-Residue option:
Girlz Only Dry Shampoo - 200ml Varieties: $3.50 per bottle / $1.75 per 100ml
Girlz Only Dry Shampoo - 400ml Varieties: $5.50 per bottle / $1.38 per 100ml
Thanks @eyzonme for bringing up the Target Girls Only option.