I will make it simple - make Thunder Lizard's Hide available for alliance. Either make the vendor neutral, or give alliance the same item for the same price. Even the database suggests (wrongly) that the vendor is neutral.
Now if you wanted it to be horde only or shaman only, that's ok. But both sides have druids and since this item can be BIS in a certain build, both side druids should be allowed to have it.
I am writing this for visibility since this is now 4th post on the same topic.