Welcome. Concerning the PE releases you asked about, there are only 6 OB releases that I know of, the 5 "limited edition" annual releases (who knows how many more will come out) and the rare (and it actual is) and very, very, very expensive Port Ellen Maltings.
I believe you can still get the 2nd through 5th Annual releases at Loch Fyne Whiskies (http://www.lfw.co.uk
) at very reasonable prices. I am afraid I can't give you any help on the 1st release as it seems to be sold out at most retailers.