Here's the link to the pricing platforms

At the bottom of the table is the Digital upgrade, with the price of $19.99

Collector's Edition Digital Upgrade** (Requires Base Game) $19.99
** The Collector's Edition digital upgrade offers customers the ability to upgrade their standard FFXIV account to digital Collector's Edition status via the “FFXIV Service Center” website that is scheduled to be opened at the launch of official service, which then grants the in-game bonus items included with the Collector's Edition. Customers in possession of the Collector's Edition for either version 1.0 or A Realm Reborn will receive these Collector's Edition items without needing to purchase the upgrade.

Please note that the base game is required to utilize the Collector's Edition digital upgrade.
The "base game" will be your free ARR download you get for being an original 1.0 account holder.