You may think it's impossible this late in the game, but it's never completely impossible. Between your friends on the Faceplace and random Craigslist serendipity, there are still some Burning Man tickets floating out there waiting for you to find them. I mean, 70,000 people... there's gotta be, right?
One ticket just went up for sale this morning for $350, and someone is surely jumping on that. (You'll want to sit there and click refresh all morning until that happens again.) And as BrokeAss Stuart points out, another pair of tickets went up yesterday from a generous couple who've been to the playa many times, and who are gifting their tickets for the tidy sum of $1 apiece to whoever writes the best essay about why they need/deserve to go to Burning Man. They're making their decision today, and I'm going to suggest you play up a personal tragedy angle. Just sayin.
Also, this fine-sounding gentleman is offering up one ticket for $400 and a ride, and as he puts it, "No I will not be a stage-5 camp-clinger for your group nor is this one of those creepy 'I am a wealthy gentleman looking for a female to camp with' type posts." He just needs you to have a vehicle with room for him and his shit, which includes two 7-gallon water jugs, 3-4 bags, a cooler, and a bike.
Other options: Become an attractive female model and hitch a ride with some tech billionaires (it's totally not prostitution); or parachute in and run really fast when you hit the ground, because don't think others haven't tried that. Security will chase you.