Choosing EXW because the quote looks cheapest
The mistake
A New Zealand importer agrees EXW at the seller's factory because it reads as the lowest price on the table. Under EXW the seller only has to make the goods available on their own floor. Everything after that is yours: loading, inland haulage at origin, export clearance, main carriage, insurance, import clearance and final delivery.
Why it costs money
In most countries only a locally registered entity can make the export customs declaration. A New Zealand buyer cannot usually be the exporter in China, Vietnam or Germany without a local agent, so you carry the compliance exposure for a declaration made on your behalf. The seller is also not obliged to load the goods, and if they help, the loading happens at your risk. By the time you add origin clearance, loading risk and the cost of running logistics in a country you are not based in, EXW is rarely the cheapest option it appeared to be.
The fix
For most New Zealand imports, use FCA at the seller's premises. You still control the main carriage, but export clearance stays with the seller, where the law expects it to sit.