Go to the CAA website it will tell you everything you need to know about importing/certifying.
The biggest cost I'd say is freight, you could spend as much as US$5K on freight or more, which pretty much neutralises the advantage of the good US dollar.
We looked at several options in the US but ended up getting a fantastic deal for what we wanted within NZ. I'd check out Southern Aircraft or DTI Sales they will put you onto something from within the country, much cheaper.