The best source I found is from Primaforce. For 1 Kilo, it's $32.00...And IMO the best quality for the pricing.
Supplement Facts
Serving Size: 1 Scoop (4.5 g)
Servings Per Container: 222
Amount Per Serving
L-Glutamine 4.5 gâ€*
* Percent Daily Values are based on 2,000 calorie diet.
â€* Daily Value Not Established.
Suggested Use:
As a dietary supplement, mix 1 scoop (1 teaspoon) into 4 ounces of water or juice after training and
1 scoop prior to bed-time. (told you so

)