[Is anyone familiar with this Flex face Extrusion?]

Steve is right it is a ABC flex system.  They are out of Fort Collins, Co.    https://www.abcsignproducts.com/extrusion/retro-frames 

[Do we have a member that sells extrusions???]

Brian - if you are just looking for a "H" divider and not a 1-1/2" or 2-1/2" divider bar.  Admiral (http://www.admiral-wholesale.com/dividers/) has one or maybe Excellart.  For all other options SignComp (http://www.signcomp.com/category_all.php?cat_id=29) would be the company that would have the most divider bar options.