I generally order from either Netrition (access through
www.leanandstrong.com and they get a little kickback to help keep the website going!) or
www.vitaglo.com.
Now, I'll only post that info 1,393,498 more times!
Both sites are WAY cheaper than going to GNC or (gulp) ordering directly from EAS, and I've had good service from both. Generally I only order Labrada glutamine, Myoplex Lite, and the occasional bottle of Udo's Choice (which is pricey so I don't use it often). A tub of glutamine should last you at LEAST three months.