There are nurseries (day care ) for kids under 5, some of these also provide a before and after school care for older kids where they drop and pick up the kids to/from school. Our school has a YMCA care on site which provides the school kids with before/after school care and also vacation care. Its pretty good value too compared to others. There are lots of YMCA childcare places around Perth, just google. Some people use childminders (called family daycare I think here) but I think they are harder to come by.
The cost of the daycare for our local nursery is $80per day and the Ymca after school care is $30. We get around 50% of this paid by centrelink. The vacation care is $60 per day and again half of this is covered. Depending where you live, costs can be higher.