It’s been available via the developers’ website for a short while now, but Carenado’s C90B KingAir is also now available here at simMarket.
If you judge popularity by the number of repaints available then the C90B is definitely collecting fans by the cabinload, with repaints varying from FAA test aircraft through flying doctors and corporate carriers to USAF trainers available from the freeware download libraries. The pack is for FSX only, with a custom avionics suite and high quality textures. Full details can be found on the product page.
It also comes with “3D Stereo” sounds but, if you prefer, Arezone have also released a C90B soundset which they say is recommended for use with the Carenado aircraft.