do you sell a replacement home button?

I did not find it on ifixit but you may send your request to http://www.ifixit.com/Info/contact otherwise the button is available online at many places like this Amazon and ebay has plenty of those as well. To replace it just use this guide as a general starting point. Look at the photo on step 17 you see a white disc in the bottom middle of the photo. That is the home button. Make sure the disk is still on center and has not slipped. I would pry it up gently, it's glued on with a rubber cement like glue.There is a small metallic disc on the underside of the white disc. Clean this with isopropyl alcohol.On the logic board where the disc was there is a metallic gold ring, clean the gold ring gently as well. Now carefully align the white disc back over the gold ring and tape in place with just a small piece of tape. There are also plenty of helpful instructions online at Instructables and here and finally here. Good Luck to you.