Try an Asian grocery store.  Order from them in bulk, making sure you are 
getting raw, not hulled or roasted, seeds.  Also check out the internet, 
speaking 
with a representative to make sure you are getting the raw, unhulled variety. 
 One Silver List member found them at BulkFoods.com.  I don't know if they 
are raw, unhulled.  Sesame Tahini is a healthy product, especially if it is not 
roasted, but I believe they use the tan seeds instead of the black, and these 
are not as beneficial.  Why not use the unprocessed, raw, unhulled seeds, keep 
them in the freezer until use, and them grind them daily--perhaps with flax 
seeds to get the optimum effect?

Jill