So on the front page it says that the items in the event shop are half off. But when I go there I don't think any of the prices are different. Has the sale already happened and been ended or is the announcement up early? I really want to get some items in the shop but if they are going to go on sale I don't want to get them yet. Does anyone know what is going on?

They are on sale. :)

After the event is over, the prices you see now will double.

Everytime there is an event, there are items in the event shop. After the event, the items move to other shops and are from then on sold for double the price they were in the Event shop. That's why there's a message saying you can buy them now for half the price. ;) Also, you can buy those items with candy apples now (by clicking "buynow" instead of the coin), when the event is over you'll have to pay with gold.