According to this morning's copy of the UFC Newsletter:
Due to incredible demand, nearly all of the tickets to UFC® 83: SERRA vs. ST-PIERRE 2 have been purchased by members of UFC® Fight Club in its exclusive presale which started on Sunday. Over 21,000 people will rock the Bell Centre on Saturday, April 19th, and the vast majority of them will be UFC® Fight Club members. The UFC® organization is honored to welcome so many of its most devoted fans to the event that night.
Because of the unprecedented size of this presale, the normal UFC® Newsletter Presale will not take place. The scheduled public onsale date for this event is this Friday, February 8 at 12pm ET. On that date and time, a very limited number of tickets will be released for sale via Ticketmaster and at the Bell Centre Box Office.
Additional viewing options for fans in the Montreal area, or those wishing to come to Montreal for the event, are currently being researched. Information will be made public as it becomes available via UFC.com and this UFC® Newsletter.