Having just gone through a pretty exhaustive online search to find just the right monitor mount, I know wading through them can be a difficult task. Most sites aren't set up to allow you to filter for specific features of a mount.
One of the sites with decent filters is Wayfair...
http://www.wayfair.com/Computer-Mounts-C1824156.html
Unfortunately the reach isn't one of the filters. But perhaps you could start with wall mount and articulating arm.
If you can find a Chief within your specs and budget, go for it, they make excellent mounts.