For the celebrations, Stardoll has released a store dedicated to Hello Kitty. The store can not actually be seen yet, but you can get them all in your dressing room by clicking here (be already logged into Stardoll to see them all).
(Click to enlarge)
All are for non-superstars except for the jumpsuit thing and the nightgown. They are all at a reasonable price (4sd-6sd) and can be easily bought with your play and earn.
P.S If you visit my suite, you will see that I am wearing the white hello kitty shirt which is in the upper-right of the store.