Milford Sound and the Great Walks are the real deal. If you want to hike the South Island without getting soaked or frozen, aim for shoulder season around October to November or March to April. That means booking your long-haul flights roughly six months out to snag decent routes and reasonable prices.
A trip like this usually runs about $4100 once you factor in flights, campervan rentals, and trail huts. Instead of dumping that all on one paycheck, you can break the bill down into monthly payments over a year and a half before you ever pay a dime in interest.
Remember, 0% interest is a deadline, not free money. If you still have a balance on your Citi Simplicity® Credit Card after those 18 months wrap up, the standard variable interest rate kicks in on whatever is left, which gets expensive fast. Stick to the $227.78 monthly plan to keep it at zero.