Ok....well, if there is ever a safe place to buy stuff online, its this site. In addition to that, there are very few powders out there which contain the amount, and the high quality, micellar casein and whey isolate that Low-Carb Metabolic Drive does, nor are there any, in my opinion, that taste as good. It will also be hard to find powders that fit carb and calorie guidelines.
GNC does have a protein called PM Protein which is Whey Concentrate and Calcium Caseinate, designed to be a blend of fast and slow digesting proteins, respectively. Tastes like crap. Quality is probably questionable. Most of all the other proteins at GNC are whey, and are lame. A few rare blended proteins include:
Optimum Nutrition Pro-Complex (whey and egg)
Xyience X-Protein (whey and egg)
Syntha-6 (this is a micellar and whey blend, but I suspect it has a lot more whey than micellar casein, and also has added fat and is fairly high in carbohydrates, even with the high fiber content, for the amount of protien you get. I don't think you could really do the V-Diet as written using this shake)
GNC sells HOT-ROX Extreme, but it is not the same formulation as designed on T-Nation. I believe the HOT-ROX Extreme at GNC has the XXG blend, which contains the guarana-berry extract and theophyline, whereas the T-Nation version is the XXX version.
If I had to venture an educated guess, the XXG version is going to have a stronger stimulant energy effect (the masses like to feel their fatburners), while the XXX version is geared more for muscle mass preservation (even though it gives you lots of energy too.) Could be off base with that though. Anyways, you'd still be ok going the XXG route.
The GNC branched chain aminos are laughable, if you were planning on supplementing with branched chains.
You could use their flaxseed and fish oil, but be prepared to take a lot of fish oil pills. You may not care - I don't. I take a shitload in addition to Flameout.
Most GNCs are not going to carry a post-workout recovery shake that even compares to Surge.
I'd strongly urge buying Biotest, like you anticipated.