Short answer: Yes. Need ~$385/week for $30,000 deposit. Requires aggressive saving and discipline.
Yes if you save aggressively. For a $30,000 deposit (5% of $600,000), you need to save $1,667 per month or $385 per week. That is hard but possible with discipline. Cut discretionary spending, take extra work, or move somewhere cheaper. Use a separate savings account so you cannot touch it.
Target: $30,000
Weekly Required: $385
Monthly Required: $1,667
Kiwi Saver Contribution: $200/month
Savings Needed: $1,467/month from other sources