You think our Cash shop is bad...take a look at THIS

[Skivvy]

Weddings (Eternal Bond) are free. The extras cost more.

I actually forgot they have a completely free version, but regardless, the higher packages should be something that you can obtain with in-game gold. They could make it cost quite a bit of gold, but it should be something that people can work towards in-game.

Then new players or existing that missed the event will complain about them not being able to get the item cause they missed the event. The Gold Saucer could used for this but without the cash shop it most likely would just become a unobtainable item which circles back to the first part of my post.

I'm not quite sure which way you're leaning on this one, but what is wrong with people who were not around for previous events NOT being able to obtain a special item?

As Risvertasashi mentioned above, an easy solution could be for them to sell the previous event gear at the NPCs for a nominal fee while the current event is going on. XI does this, and I believe XIV used to do it as well. So those new players could still get their spiffy gear, they'd just have to wait for the actual event to come back around.