Guild Wars 2 is available for pre-purchase from a variety of vendors. The digital versions of the standard and deluxe editions can be purchased on Guild Wars 2's website, although ArenaNet has also posted a list of retailers that are selling the game. It's only through these retailers that physical copies of the standard and collector's edition can be obtained.
As of the time of this writing, many tipsters have reported that GW2 collector's editions have been sold out at several retailers. ArenaNet said it will have an update in a few hours on Twitter.
By pre-purchasing Guild Wars 2, players not only get the game itself and any goodies that edition contains but will secure access into beta weekend events and the game's three-day headstart prior to launch. The standard edition is $59.99, the deluxe digital edition is $79.99, and the collector's edition is $149.99.