The audience for some top-name music acts apparently is shrinking. Denver's Rocky Mountain News reports that David Bowie, Moby, Busta Rhymes and the Blue Man Group, who were scheduled to perform this month in the city's 18,000-seat Pepsi Center as part of Moby's Area: Two concert tour, have had the venue of their concert switched to the 5,000-seat CityLights Pavilion, owing to a lack of ticket sales. And some lesser acts are even having trouble fill, ing that smaller arena. The News states that the Roy Haynes and Michael Feinstein concerts scheduled at CityLights for later this month have been canceled altogether. A concert this week by John Mellencamp at Colorado's Fiddler's Green had only sold 5,000 tickets prior to showtime in the 18,000-seat venue, reports the News. While these may be deemed isolated incidents, music promoter Barry Fey blames the depressed national economy as well as some internationally known rock stars who are commanding outrageous ticket prices. "They're shooting themselves in the foot by charging $150 and $250 for tickets," Fey told News music columnist Penny Parker. "Why do the (Rolling) Stones have to charge $300 for a ticket? Why did Paul McCartney, who is a billionaire, need a $250 ticket? Why?"