Real Gains off glutamine? You're not going to see physically "gains" off glutamine. Glutamine is anticatabolic and is better used while cutting to preserve muscle.
Invest in the peptides. You'll get better absorbtion, and more bang for your buck. If you take just plain l-glutamine, never take it with a protein as they both compete for absorbtion through the same pathways. With the peptides you won't have this problem.
It isn't as readily available as the non-peptide bonded glutamine. Your best bet, and most likely cheaper option, would be to go online. I personally get mine through the use of Muscle meals meal replacement by Muscle-link. Each packet provides 10 grams of glutamine peptides. Check out dpsnutrition.com or theproteinfactory.com for bulk purchases. The cheapest but not most reliable, in terms of in-stock items, is nutritionmegastore.com. They are dirt cheap, will cut the price even more for bulk deals and provide free UPS shipping on orders over 100 bucks.