Meh, I've been to Bonnaroo 4 times and with a little scheming spent an average of $250 per trip. I bet even the lowest estimated "full price" of $500 is less than some of y'all spend in a regular week.
You can fly to London with airline reward miles and stay with friends. You can also buy a first class ticket, stay in hotels, and buy your scale model of the Millennium Bridge and 27th edition vinyl of London Calling. It takes all kinds.