My Westin Platinum series came this afternoon so I had a chance to get the drivers side installed on my lunch break ($321.69 inc shipping from pickupspecialties.com). They aren't completely C-shaped. I was hoping to avoid potential end-cap issues (getting them knocked off). These do have plastic end-caps. I guess you can't have a C-shaped nerf bar unless the attachments to the truck are at the ends. They attach to the body of the truck, not the frame. Brackets are very sturdy. They sit relatively close to the body compared to some others I have had.
As you can see from the shipping box, they are thick but the CrewMax makes them look skinny in the pics.