Just be aware that the bonus item codes that come with merchandise (artbooks, soundtrack albums, plushies etc) have a use-by date on them, so if you happen to acquire the item voucher after this date they will no longer be redeemable.

As far as I know, the only one that is currently affected by this was the Wind Up Dalamud minion that came with the Before Meteor Blu-ray soundtrack album (the code for which became invalid at the end of 2014), but the Wind-Up Bahamut minion that comes with the ARR Blu-ray soundtrack will also similarly become unattainable on December 31st 2015. Other current bonus items still have over a year or so before their code use-by dates expire.

So just be aware of this.