Well my best friend owns a sound production company and has worked alot of 12-15 thousand seat events... anyway. He told me a show the size of GNR's if they were on tour would only cost about 50-100K per night depending on a large number of things.... this of course does not include the band's pay... only the cost of production (ie speakers, power amps, lights, crew's wages, etc etc). If it was a one off show the cost would be much more. probably double.
Yeah, that sounds about right.
When I figured out my guess, I'm figuring about a 200k a night in "wages"..for the band, their roadies, etc, etc.
Add in advertising costs and some other miscellaneous "stuff" like facility charges, insurance rider, etc....