I admire anyone who can take Spirulina in powdered form - I would not be able to get past the aroma
I get my tablets online from I Herb. I order the "Now" brand and get the bottle of 500 tablets of 500mg each. I can't remember the price right now, but I know I researched a bit and they were the best bargain online that I could find.
I usually order two bottles at a time to save on shipping and handling. The next time I will order four bottles because two only last me about a month and a half (Raymond takes it as well). And it is made from spirulina grown in Hawaii.
We (PATHS) may have private-labeled spirulina available to us down the road. I am not sure how far away we are from that though.