Why do concert tix cost so much?

It annoys me how much concert tickets for good bands cost. I am 13 and I have never been to a concert because I don't wanna pay 100 bucks for ONE ticket and neither do my parents. But I do wanna be able to say that I went to a concert at least. Isn't there some way to get better priced tickets? I looked at Metallica, Megadeth, and U2 tickets. Of course they were all 100 dollars each. That was for general admission. Don't some concerts have like tickets prices depending on how close you are to the stage?