The Magic Travellers Network is a good alternative to Kiwi Experience. The Magic bus caters to independent travellers running along a fixed route and giving travellers the option to get on and off the bus whenever they wish.
Travellers have up to six months to complete their journey.
Like Kiwi Experience the various passes are restricted to a particular route, however it's easier to work out which pass will suit you best. New Zealand Magic Adventure Covering all the main sights from Auckland in the north south to Wellington. Covers both the east and west coasts of the South Island. New Zealand North and South From Auckland in the north heading south to Wellington. Covering the west coast of the South Island as far south as Queenstown and then continuing to Christchurch via Dunedin.