That's an Aliexpress dropshipper. That exact dress is all over Ali for about $15. Just get it directly from there. I have a few in similar styles from AE (dropshippers sell a version on Amazon here), and they're great quality. Nice light fabric, comfortable to the point of feeling like I could sleep in it.

You can reverse image search on both Amazon and Aliexpress via the apps (or for AE, aliseeks.com)