Ok guys, thanks to Steve's recommendation, Alex from 350z-UK managed to find me brand new door grip and silver finisher for the prices:
L/H grab handle £27.58
L/H grab handle finisher £41.34
(postage not included but guessing it'll be around $20)
This is still less than half price of what Nissan quoted.
Here's the link to Alex's sub-forum:
350Z-UK.COM The Nissan 350Z & 370Z Owners Club • View forum - ZMANALEX
Kam80 - araldite and then fibre-glass filler will make it stronger than new. Just don't use too much otherwise the finisher will not fit properly and you have to sand it down.