New Zealand - South Island
Below is a map of the South Island
Alternative route Christchurch to Invercargill via south coast 575km (155km shorter and less hilly but miss scenery)
Flight Invercargill to Auckland 3-4hrs NZ$258 + 20 for bike (£100)
Low bus fares if booked in advance, not transferable or refundable, limited numbers, Bikes cost 10 NZ$ per leg and carriage subject to space available
Bus Invercargill to Christchurch 10hrs one per day (0845-1840) NZ$ 44-77
Bus Christchurch to Wellington 9hrs two per day (0700-1600) NZ$ 75-116 including ferry
Night bus Wellington to Auckland 10.5hrs six per day (1950-0650) NZ$ 20-120
Total bus/ferry fares 139-313 NZ$ (£51 minimum) 2 days + 1 night
Wild camping not strictly legal, but possible in thinly populated areas dusk till dawn