Hi oakwalker, the fight sold out the first day, so I don't believe you will find a ticket. Scalpers and ticket agents are a possibility, however they are being sold at a significant premium and will be significantly higher than the face value which ranged from $350 to $2,000 (Please know that the $350 seats are very bad quality and you will be watching it on the screen).
The best alternative is Closed Circuit. I believe the MGM closed circuit is sold out but Mandalay Bay would be a good choice. The price is $111 and change.
I am sure tonyrob's link would be a good way to proceed, but I had trouble accessing it. If you also have issues with it, just go to the ticketmaster website to buy the closed circuit ticket.
I have been to many fights in Las Vegas and I would recommend good cards to anyone. They really are special.
