Arashi Waku Waku Gakkou @ Tokyo Dome tickets will be available to the public. ^^

Participating ticket agencies listed on JNet will start selling the tickets on Saturday, 18 June 2011 from 10:00 a.m.

Price: 4 000 Yen (~US$50)

I added the websites for reference.

CNプレイガイド ：（初日特電）0570-00-0056
CN Play Guide: cnplayguide.com

ローソンチケット ：（初日特電）0570-00-0013
Lawson Ticket: l-tike.com

イープラス ：（初日特電）0570-06-9930
E Plus: eplus.jp

チケットぴあ ：（初日特電）0570-02-8813
Ticket Pia: t.pia.jp

キョードー東京 ：（初日特電）0570-08-9988
Kyodo Tokyo: kyodotokyo.com

If you're in Japan, it's worth a shot to go to Arashi Waku Waku School. ^^
Good luck!