Wow, I am surprised. Most health food stores will carry Psyllium ans psyllium seed husk. The husk seems to work best for me. Some people recommend powder, but I find that it is too binding. Look for a Colon Cleanse in the health food store, often that is what psyllium is sold under if it is not sold in bulk. Some companies will package pure psyllium and sell it as a colon or bowel cleanse.
If you are living in a small town and have a dry goods supplier, they might have it. Otherwise, keep digging around on-line. I am sure it is out there.