It costs 9000 HUF (35-36 euros), and I think you can buy it on the venue, since as far as I know half of the tickets are still available. The concert will take place at Petofi Csarnok (Pecsa), Pest. You should take the 'red' subway from the Parliament to Deak ter/square, and then change to the 'blue' subway line, get off at Arpad bridge, then take the tram (No. 1.) to the direction of L?gym?nyos, get off at the fifth stop (Erzs?bet kir?lyn? ?tja). Then ask someone
(If you wanna meet me to be sure to see the show, send me a PM.)