physicianformulas.com
I buy it from there, but they have it lots of places, its pretty cheap. They have it at Whole Foods, for example. I wouldn't take more than 1 50mg pill every two days. I think all the over the counter anti-depressants are cheap except for SAMe, which is pricey. St. John's Wort, 5-htp, tyrosine, they are all inexpensive.