The key to finding what you're looking for is by figure out what it is called!
In this case, the hardware is referred to as horseshoe flat track. And here you go...

http://www.realcarriagedoors.com/hardware-cat.php?page=sliding-hw

http://www.barndoorhardware.com/flat-track-hardware/horseshoe-flattrack.html

http://www.realslidinghardware.com/horseshoe-flat-track-kit/

and then you can search to your heart's content! I'd have trouble choosing which one I liked best.

:) Rhoda http://www.billfryconstruction.com/

You can try barndoorhardware.com.