We found that the pet transporters from the US only charged a reasonable fee ($400 USD for 2 dogs) on top of other fees we would have needed to pay anyhow (official inspections and pre-boarding vet checks, freight fees etc etc). You don't have to use a pet transporter coming from the US, but there's a lot of minutiae necessary for NZ to approve entry of the animal, and I felt $400 was a decent price to pay for not having to learn about how to arrange a USDA inspection and hang out at LAX cargo area.
Do you know what those fees are for you and how much you would save doing it yourself?
Our shipper cost for 2 dogs (about 40kg of dog altogether not including crates) was around $2500 USD with a further umm $3000 or so NZD for quarantine (in the same kennel). There was also another 1-1500 USD in vet fees and tests.