This one's for Escada.
My current collection is by no means complete. One of my greatest joys is collecting the pretty dresses, pets, and mounts that Warcraft has to offer, but I'm limited by the time the events run.
Collections. Dustfire's was made over the course of 2 years. Birdfall's has only had a chance to grow for half a year, since I remade her so recently. Please note that I don't include some very nice tailoring items due to their unlimited availability and bag space being at a premium.
There is one dress in the game that is (debatably) more rare than the Easter dress. This is the Formal Dangui which shows up on a vendor in Moonglade for 50g once every 2 months or so. I haven't been farming this dress, but my friend has because it can accept item level 60 enchants and has no level requirement to wear (thus, a fantastic twink item when Northrend enchants come out).