I don't know where you're located, but I would recommend googling motorcycle salvage yards in different cities, then just call and ask.
I was just in San Francisco, and they had a HUGE warehouse of used Jap bike parts. I think its called Cycle Salvage, and its in Hayward. I had bought a 1980 yamaha xs650 for 100 bucks but it only came with the frame, wheels, and engine. I understand it is more popular of a bike than our CM250s, but I found everything at that shop I needed to rebuild it, except the gas tank.
I'd check it out, if not, just find more shops and call around