This is the instructions on how to just remove the bottom cover to access other components. The part is sold here on iFixit for $99 and looks to include the rubber feet.
The back cover is sold here and can be found at the top of the page.
These are instruction on how to replace the cover as if it came with the screws and rubber feet. There are other tutorials on this site on replacing the rubber feet and they do sell the bottom casing (with the rubber feet) and screws here.