Just to add to the statistics, I've been doing Sha on 10 characters, using coin every attempt for 2 months now, that is ~200 personal roll attempts and not seen or heard about anyone actually getting it in the raids, that is ~4000 player rolls not including their possible coin rolls (10 chars, 10 weeks, 40 players).
Yes I'm a mount collector and last I checked #13 in the world
http://www.guildox.com/go/g.aspx?a=19 - So if I have done these 200 personal attempts for no reason (including the elder coin farming on 9 alts) I will be a very sad panda...