Genuine Dell parts are generally available on the Parts-People site here. They are out of stock on that cover at the moment but if you contact them they may be able to give you an in stock date. You can also get the part number for that base cover there and using that search the Internet.
I am trying to determine whether the owner of an XPS 17 9700 can replace its base cover with a pristine new cover. Is such a part, a brand new one, available for sale somewhere?   I'm not having any luck with an online search. The Dell website is not a help. I had to open my 17 to replace a dying battery. I had the tool for prying the thing open and was able to do so but the process scarred, in a few places, my base cover; and I'm curious. If I wanted to just go ahead and replace this piece for aesthetic reasons, is it feasible? There was nothing clear and reliable looking on ebay.   Thanks.   
New OEM XPS 17 9700 Base Cover Parts, available for purchase?