The new Yongnuo YN 50mm f/1.8X DA DSM PRO lens for Fujifilm X-mount will be officially announced later this month (June).
In the US Yongnuo lenses are sold at Adorama, B&H, and Amazon.
Yongnuo to announce new 23mm f/1.4, 33mm f/1.4, and 56mm f/1.4 APS-C lenses