Replacement round black cushion pads for MacBook Air

i'd say your best bet is to get a complete new bottom case. MacBook Air (Original) Lower Case . of course, this part is listing for the original Macbook Air. if you ahve a different model, just check for it here on iFixit. http://www.ifixit.com/Mac-Parts/MacBook-...

i don't know of anywhere to get it seperately. If anybody has a source for them, please let me know, i've been looking for a while myself for a few clients who do not want to replace the entire bottom case.