I should let you know that only the hoodie is a common item that you can purchase in the shops. ;3

The others are rare items. There are 10,000 of the hairpins, so you should be able to find one fairly easily (if not from other users, then the Quester's Raffle in the Quest forums or the Giving Back Auctions in the Exchange forum).

The balloons and tee-shirt are part of a release of 1,000, so they are much more difficult to get a hold of.

And the ears and tail are Halloween '07 items. Haven't looked it up to see how many of those there are, but people do still sell them fairly regularly, or use them as prizes in contests - so they should be easier to get a hold of than the Welcome Set (the tees and balloons). :3

::loves kitties too:: >_>