Dr Clark's product is the best, I agree. However, it is SO much cheaper to make your own. I've made mine for years.I used Hulda's recipe; I freeze the nuts until I need them. It's very easy. I make small amounts at a time [only 1 green walnut at a time] because when the tincture turns brown it's almost a waste of time to injest it.
Dr Clark published a study on why the tincture must be green in color. It is very potent when it's still green.