There's defitnitely some good prices for Primaforce. One brand that is cheaper for glutamine (but not as cheap as I was thinking) is Higher Power (BB.com). $29.99 or 1000 grams so that's 13 cents a serving as opposed to 14 for Primaforce. Also it's micronized glutamine. Not a big difference but it all adds up.
(You may have heard that Higher Power had problems with the purity of their CEE product, but so did a whole bunce of other brands, and some still do. A lot of the stuff is coming from China and is just creatine or even mostly creatanine. Higher Power fixed their CEE and I have no reason not to trust their gluatamine.)
However, the champ is Puritan's Pride. The disadvantage is that you have to wait for their 3 for 1 sale, but they come around often. You can get three 300 gram containers for 14.49. That's 7 cents a serving! I've seen their glutamine writeup at ConsumerLab.com and it's pure all the way through.
Now, I can't guarantee Higher Power, but I think Puritan can always be trusted.