It depends on the event, artist, and venue. I'll buy from scalpers so I'm willing to pay more than face value. I'll pay more for smaller venues.
The most I've spent on face value tickets was $400 for Bon Jovi for the Hard Rock Hotel in Florida--not worth it. The casino setting limited their show to a shorter set than normal.
The most I've paid for charity was $500 for Keith's Max It Out benefit which was worth every penny and more. The proceeds went to meningitis research. The package included a swanky private dinner with Keith, Richard Marx, Katrina Elam, and Keith Anderson doing acoustic sets. Then the main event put me 4th row (later moved up to first row) and Keith's guests included Tim McGraw, Faith Hill, Montgomery Gentry, Wynonna, Katrina Elam (again), Richard Marx (again), Leanne Rimes, Carolyn Dawn Johnson, Radney Foster, and others I'm forgetting. The dinner started at 6:00 PM and Keith ended the concert around 2:00 AM.
So, lets say there's a hypothetical 6 hour concert benefitting charity at the Ryman Auditorium in Nashville featuring Bon Jovi, Keith Urban, Nickelback, and Chris Daughtry..... my bank account would be in danger of taking a MAJOR hit.
The only thing I can say is I would never pay more for a concert ticket than I could afford to pay off immediately. I will not go into debt for entertainment.