If you import parts, it is possible to bypass the brokers if YOU pick
up the item at its point of arrival in the country and take it
through Customs yourself.

I did this with my Porsche G50 trans. It was a hassle, but it would
have bypassed the hassles of brokarege (in fact I HAD to do it
myself, as there was no broker involved; it came in in a container,
with no broker). It was SUPPOSED to be delivered straight to Dunedin
(right in the south of the South Island), but instead ended up in a
holding firm's warehouse in Auckland, near the other end of the
country. I had additional hassles here, as there was no communication
between authorities, but finally I managed to get it sent down here
and run it through Customs procedures at this end.

Best by far to use normal mail where possible, as the mail folk I
think cannot be bothered with mucking around on behalf of Customs. I
have never been charged duty or GST (12.5% Goods & Services Tax) on
mailed goods such as my South African grills (which came in surface
mail).