Shortly after announcing Black Sabbath will headline this year’s Lollapalooza festival in Chicago, three-day passes for the event sold out. Secondary ticket brokers are hoping music fans will turn to them for their ticket to the popular music festival.

Lollapalooza, taking place August 3-5 at famed Grant Park, brings music and culture to thousands of fans each year. According to Chicago-based radio station WBEZ 91.5 last year’s 20th anniversary of Lollapalooza drew an estimated crowd of 270,000.

With Black Sabbath on board, the festival is likely to attract a very large audience. According to Rolling Stone, the event will be the legendary rock band’s only North American show of 2012. After turning down performing at Coachella when band member Tony Iommi was diagnosed with lymphoma, Lollapalooza founder and Jane’s Addiction frontman, Perry Farrell, was doubtful that the band would be playing Lollapalooza.

“Every festival in the world wanted Black Sabbath to perform, but at the time of the announcement they had to back off and cancel all their shows,” Farrell told Rolling Stone in a recent interview. “They mean so much to me, and they mean so much to music in general, that I kind of feel like I’m dreaming to know that Black Sabbath is actually gonna perform at Lollapalooza,” said Farrell.

In addition to the headliner, several popular acts will co-headline the event including the Red Hot Chili Peppers, The Black Keys, Jack White, Avicii, and Florence and the Machine. A complete lineup is available on the Lolla website.

Since its inception, Lollapalooza has grown to encompass 115 acres, multiple stages, and over 130 artists along with several vendors. The festival, which was originally created in 1991 by Ferrell as a farewell show for Jane’s Addiction, grew into a “larger-than-life musical roadshow,” which traveled the country before settling down in Grant Park in 2005. It was a way to introduce up-and-coming artists to music fans before the Internet became popular.

Now the festival utilizes the Internet to promote its event and build fan interaction. While a listing of activities has not yet been released — one of the more interesting activities from last year was the Sony Bloggie Borrow Bar that allowed festival goers to borrow a Bloggie Touch HD camera to record footage, which was later uploaded for sharing.

This year fans can create a custom lineup of artists they plan on checking out while at the festival on the Lolla website, which they can share and compare with friends via Facebook.

iPhone and Android users can also download the official Lollapalooza app. With the app, users can browse the 2012 lineup, create a personalized schedule or sync with one already created, setup a group chat using the app’s GroupMe integration, and listen to playlists of past and present Lollapalooza artists. Another feature is the fully-interactive map of Grant Park allowing users to drop a pin and share their location with friends.

Early bird tickets for the festival went on sale March 27 for $200 followed by regular three-day tickets for $230. With both sold out, only single day passes are available for $95. Fans looking to splurge can purchase a VIP package for $1050 per person which includes VIP access to Lolla lounges, golf cart shuttle service between lounges, premium viewing platforms, beer and wine served all day, catered food, mini spa treatments, and air conditioned restrooms.

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TicketNews spoke via email with Will Flaherty, director of communications for SeatGeek, who said that consumers are likely to head to the secondary market for passes, especially in the case of a sellout. “As is often the case too with music festivals, you’ll see a healthy percentage of individuals who purchase tickets speculatively with the intent of reselling, so there’s generally pretty large supply of passes on secondary markets,” said Flaherty.

According to Flaherty, the profit margin in 2011 on Lollapalooza tickets was much greater than this year — in 2011 the average resale price of a three-day pass was $338, whereas the face value was only $215. This year, the average resale price thus far on a three-day ticket is $265 compared to a face value of $230.

In terms of profitability for secondary market resellers, Flaherty believes that “although Lollapalooza does generate revenue for resellers, prices always will fall the week leading up to the event, so those stuck with lots of inventory at that time may end up seeing some losses this year, particularly as the average margin between secondary prices and face values is much narrower this year than last.”

With three-day passes sold out, it is likely that fans eager to attend the entire festival will turn to the secondary ticket market, despite having to pay extra fees.