jonas brothers?

how much is a typical jonas brothers concert ticket? I mean i wont be able to go this year because i live in MA and there are no more jonas concerts here but, im planning to go next time they come here. and btw if you are under 18 do you need to go with someone who is over 18? This is kind of a dumb question but i’ve never been to a concert and I would love to go to one. Also, where else could you get concert tickets besides on the internet?