Any GC should be able to do that for you. But, you could always go it yourself!! There are a lot of companies out there that sell the hardware (and I've heard it's not that hard to do). This link was just one of the ones I found on Google when I searched.
http://www.barndoorhardware.com/flat-track-hardware/standard-flattrack/

Real sliding hardware, located in the Pacific NW makes lovely hardware for this application. Here is there photo gallery. Free shipping on orders over $300; http://www.realslidinghardware.com/barn-door-hardware-photo-gallery/

I am looking for the entire door, not just the hardware.

They also sell the slabs too! have a ook at the photo gallery.

What is generally done is that the doors are purchased from a door supplier (or custom made locally) and then the hardware is purchased separately. There are several options for hardware depending on the look that you want. Rustica makes some very nice looking hardware.

There are several photos and threads about this question here on Houzz. Try a couple of searches. Try barn doors, face sliders and look at photos. Then try the same search terms and select discussions and read through those. I can't remember what they were, but it seems several users found some good sources.

Love the look. Good luck.