My new hood liner has arrived
In the end I purchased this from BMW of Warwick thru the aforementioned Lisa, who was most helpful in ordering and getting the package to me. She personally went to her local post office to price and arrange shipping, and on top of that she threw in a complimentary pack of Twizzlers! (not partial to these myself, but it was a nice gesture all the same).
The liner itself appears to be of very good quality, arriving within the quoted delivery time, well-packaged and undamaged - see pics.
I'm sure there are many good BMW spares people out there among the US dealerships, but I can highly recommend Lisa at BMW of Warwick for straight-up, no fuss, customer-orientated service, and would certainly consider purchasing spares from this dealer in future.
Thanks again for the referral, AG. :-D