Purchased an ebay special rider back rest for the fatboy the other day, didnt want to spend a fortune as it will probably be used about once a year.  Ispoke to a guy on the Hume on the way back form a ride last year that purchased one off ebay for his fatty and he said he loved it.  No issues at all and cheap enough.  I lashed out and purchased one as well for the once a year long ride I do on the fatty and when it arrived I rushed out the back and fitted it up.