maybe prices aren't all so different then, although that was a seat, the £100 here was standing. a seated ticket was quite a lot more.
course, it's all down to what the public are willing to pay, and these days it seems that while people expect recorded music to be free, they're willing to pay through several noses for tickets! a friend of mine payed over £300 last year to see Pearl Jam, off a tout of course, but they always seem to be able to get all the tickets they want while genuine fans can't get any.
hmm, a little off topic there, sorry bout that! although it'll be interesting to see how much the Zeppelin tickets'll be, and how many show up on e-bay.