As a store manager, it comes down to this:
Metabolic Drive [metabolic drive]: Cost $0.80USD per serve, sells for $1.60USD per serve. - Profit $0.80USD per serve
Other Crappy Lowcarb product: Cost $0.50USD per serve, sells for $1.50USD per serve. - Profit $1.00USD per serve.
I know I'd like to make an extra 7 bucks off each and every customer, all while preaching the virtues of me saving him money.
Of course those figures are abstract and all, but at the end of the day he can make more by selling you shit.
The store I go to has the owner selling Grow! over other proteins, TRIBEX over other tribulus products, Alpha Male as often as possible, and using all the above himself [as well as using Carbolin 19 19 currently, to compare offhand the effects of it vs an anavar only cycle].
Just look around for a store owner who isn't a dumbshit, or if you can, buy of the T-Nation store right here.
Oh and btw, yes I use Biotest's products - Currently: Metabolic Drive, ZMA, HOT-ROX, Alpha Male. [I tried Spike and it didn't work on my dead recpetors, and I don't use Surge due to my low carb dieting].