[Taiki]

I believe that the older items will stay in the shop for people to buy after the first part of the event is over but you'll no longer be able to get Pearls. I can't say how much longer that'll be though. xP

And like Rem said, the drop rate goes down once you get enough to buy an entire set. This was done because users were saying that event currency was too easy to get in the past events. Though most people have just been switching over to a mule to get their 2nd and 3rd set. >o>;