I've bought from Fiddler'sCreekDesigns
on Etsy before. I just use the cover button kit that you see at the craft stores and do it by hand. If I need to center the fabric then I just put a little bit of glue from an Elmer's glue stick on the button before adding the fabric. I think you can even find the small kits at Wal-mart if you want to try it out.