The event tab shows special offers for the current or recently passed events.
In fact, there are usually plenty of items to choose from. The currency used for these varies from ironite, soul fragments, gold and (of course) real world dollars. Make sure you know what you're getting as some of the items are intended to finish off a set of talismans or are just some of the fragments needed to achieve a character.
I would also like to take this moment to tell you to check here at the beginning of each event for a couple of reasons. You'll quickly see if soul fragments became currency in the store, but also will be able to find free items here from time to time.
a few things to mention :