1) Nordstrom's auto. google it. you have to call them. 150 shipped.
2) A fellow TYF member posted a thread saying he was removing his roof rack and I PM'd him to buy and he shipped it to me for 175 which is a great deal. They go for 250-350 easily. Some will ask for more and they'll get it (they retail for way more then that new.)
3) I too thought I 'just needed the chrome and black piece'. Not that easy. You need the escalade/denali hitch cover, rear bumper cover, step pad, and chrome trim (seperate part with whole different part number-- snaps in with tabs onto the step pad) -- TOTALLY different then your original yukon/tahoe step pad that is one piece. This is a difference TWO piece step pad.
Pics to show the difference between original bumper and new bumper with new step pad/chrome trim:
http://s108.photobucket.com/albums/n31/felixgun/Bumper/
4) My running boards had the chrome trim you could purchase on eBay and in pictures they looked clean, and in real life, they looked OKAY at best. I also had this ebay chrome trim on the rear bumper cover when I had my 'old' nnbs original Tahoe LTZ 08 (versus the Tahoe LTZ 09+ bumper that I now have). Both started peeling and eventually I ripped it off because it looked cheap. The chrome trim on the bumper that is OEM/factory is SO FRESH compared to the ebay chrome trim I used to have. So to answer your question I did not swap them out. The nnbs denali and escalade with the manual (non-auto) side steps has a factory chrome strip that lays flush with the surround black plastic. It is impossible to put it on the factory Tahoe steps and can only be put on with 3M tape. To get the real chrome strip you have to replace the whole running board that already comes with the chrome trim on it which is actually one piece. (Two total-- one for each side, and that's all you have to get). I will eventually get these running boards but they are pricey and run about 350-500 used/on the internet.
P.S. - Thanks man appreciate it! It's a melting pot of idea's from this forum.