Review Source Naturals 5 HTP is one of the many sources I've tried. It was best tolerated at night a few hours after eating, but made me sick to my stomach if I took it before eating in the mornings. The biggest downside to the product is that it is in 50mg capsules instead of 100mg capsules. I have heard great things about Lidtke's l-Tryptophan as well, but have not tried it.
I would definately use Source Natural's 5-HTP is available to me, but prefer LifeLink and Solaray's.