Do they have any awesome, Wacken-esque metal festivals in Japan each year? It'd be cheaper to go to one of those, and at least you wouldn't have any tall people blocking your view.
I don't like very many European metal bands so Wacken wouldn't really be for me. They do sometimes have good bands like Pink Cram 69 & Jaded Heart on occasionally though, and they had Twisted Sister last year and Lizzy Borden a couple of years back.