To answer some common questions:
Material can be found on Amazon as well as the connectors. Someone posted a link above. Here is a link directly to the supplier with more options.
You can actually order it cut to a desired length from them as well but that can get expensive and also requires you to know exactly what you want ahead of time. Could be useful if you don't have a saw to cut it at home though.
I ended up ordering off amazon in 8' lengths just because the shipping was actually cheaper than ordering it directly from them. In total I was about $600 in material including shipping. Right now I have quite a bit extra to make the bed platform and drawer slide. I think I over ordered and could have done just the cabinets for maybe 300-400. The molded corner pieces are surprisingly expensive.
As far as mounting goes my plan is to bolt through the frame and floor of the van. I am going to try and avoid cutting or drilling any holes through the plastic trim pieces on the wall if I can. My family is still growing and who knows how my van will change over time. Would prefer to keep that stuff all intact for more flexibility in the future.
For the panels I will probably just use some self drilling screws to go through the panel and the aluminum flange. Ideally countersunk so the stay flush. Maybe some button heads if I run out of real estate on the edge for a countersink.
For compartments that I need to access I am looking at these hinges and latches:
I am also considering just drilling some 1-1.5" diameter thumb size holes in the panels and using magnetic latches instead. Will be much cheaper. For the hinges above I will have to notch out the flange on the frame which I think I can do pretty easily with a dremel.
Current favorite for panel material is this stuff:
Definitely on the expensive side. Probably going to order a 6"x 6" sample piece to see how it looks.
No plans at the moment to offer a kit, but that is an interesting idea. Maybe if there was enough interest I would consider it. Also need to see how the final product turns out! I will say once you know what lengths to cut it is pretty easy. figuring out how to adapt to the interior panels was the most challenging part, so replicating what I have now wouldn't be hard.