Locally, As far as I am aware the only peopleare Bunce Motor Co in Wairau Park Auckland. They import wrecks for spare parts. I have bought a few bits & pieces from them. Also I had to replace my starter motor & they charged me $ 195 +GST.
What type of grille do you have? The guys in the forum can best answer your question about air flow & bugs - I'm sure they also have bugs there!
There seems to be quite a variety on e-bay & US$66 sounds good but check out the shipping cost. I suspect for a replacement billet grille it'll be around $150 - $200 US!! The bigger the package the more you pay. At least that is my experience to date.
I've just ordered the bumper lights @ US$12.99 + $42.00 shipping. My euro taillights were, if I remember right $49.00 - shipping $160. Air intake $44.99 - shipping $80. As a direct comparrison similartaillights at Bunce sell for NZ$225 per set (new). I,m not sureabout used.

 

Welcome. I am impressed that you drive both a RHD and LHD. Some of the people(insert stereotype here)in America can barely drive one style car.