Over the past two weeks, Carenado have been posting previews of their S550 Citation II for X-Plane 11. As of today, the aircraft is now available for purchase at their website!
Costing $39.95, the aircraft features full VR support, customised flight model, PBR texturing, support for RealityXP's GTN750 (sold separately) and more.
Few business jets exist for X-Plane 11. If you wish to purchase the S550, you may do so through their website. Other vendors are expected to sell it soon.