Cathay and Malaysian Airlines have tickets that give you travel throughout the region for a fixed amount of money for a fixed amount of time that you might want to look into. CX is called the All Asia Pass and the new pricing just came out. I don't remember what it is but I believe around $1100 for 21 days with a marginal amount more to extend it. Tokyo will indeed be a budget buster (as will Hong Kong and Singapore to a much much less degree) but otherwise most of Asia is fairly inexpensive to be in.