Where can you buy washberry soap nut seeds from to grow?

Seedman.com has seeds for sale online, but you can harvest viable seeds from commercial 'soap nuts'. They are sold as husks for washing, but one or two husks in every 100 husks will contain the hard seed. They are still viable after being washed, and you will need to score or weaken the shell before planting. It will take 10 years to produce fruit.