Here is a link to the service manual for your laptop.
Scroll to p.64 to see the necessary pre-requisites and then the procedure to remove the base enclosure.
At the top of p.64 there are part numbers for the base. Depending on your particular variant, if you search online using just the part number only in the search box, nothing else, you will get results for suppliers of the part.
Hopefully this is of some help.
Find the part number on p.64 of the manual that applies to your model, (it should also be on the base enclosure of your laptop, most probably you will have to dis-assemble the laptop to find the number on the inside). Enter it into the Google search box and you will get results for suppliers. Pick the one that suits you best.
Here is an example only of what you do to find suppliers for your laptop. (I chose the first number 720226-001 just to show you what to do - be aware it may not be the part number for your particular variant as there are several different versions listed read the manual carefully to select the correct part number for your model variant features).
(click on image to enlarge it for better viewing)