I purchased my ticket for $280.
If you'd like to purchase I can provide the info noted below to confirm ticket validity.
http://tickets2.burningman.com/faq.php:
Before purchasing, find out the full name the ticket was purchased under, get both the 8 digit and separate 5 digit number/letter combo from the back of the ticket. Contact
partiserv@burningman.com with that information and we can let you know to the best of our knowledge if the ticket has been reported stolen or part of a scam. It is reasonable to pay for the face value of a ticket plus fees so calculate this before agreeing to a price. Burning Man cannot be responsible for third party ticket sales so be careful when purchasing. If you feel that you have been scammed by someone, contact your local police and report the person.