Ordered here:
https://www.ebay.com/itm/16-18-Civic-X-Sedan-RS-SI-Style-Trunk-Spoiler-3RD-LED-NH788P-White-Orchid-Pearl-/371960276370
Shipping took about 5 days, installing took about 30 minutes.
I decided to keep the stock lip in place because it's a PITA to remove and leaves a bunch of holes...