Woolies has the B.Box Tritan Drink Sipper Bottle 600mL on special for $9.00 (was $15.00), so you're saving $6 on a bottle that's actually worth keeping. It's made from durable Tritan plastic with a spill-proof straw top and an ergonomic shape that kids can grip without wrestling with it, exactly what you want rattling around a school bag five days a week. The 600mL size is the sweet spot for kindy through to upper primary, and the assorted colours mean you've got a decent shot at getting one your kid will actually claim as theirs. At full price it's fine; at $9 it's a no-brainer to grab a spare.