PC on Japanese Guild

What's the average price for buying a Japanese Guild? and how do you usually go about making a trade for that sort of thing?

Umm, there's not really any rules with guild trades, it totally depends from the situation. You have to figure it out yourself.

Some people used to do Asian guild tags for rest of the playerbase in ID1 Ascalon City if you're looking for that kind of service though, price varied a lot in those as well (saw 20k-100k) and it was a long time ago.