Examples: R-Lipoic Acid (R-ALA) ALCAR Magesium L-Threonate Mucana Pruriens Trans-Resveratrol etc Pound-for-pound of active ingredient is always cheaper than equivalent pills from well known brands (claimed higher potency of active ingredient than those from well-known brands) Seems like these powders (of active ingredient) are purchased from China or India. Many of these bulk powder sellers on Amazon, Ebay are, basically, distributors/marketers that stick their own label on the plain packaging. Some even assemble pills from the powders & sell them on that way (Reality is that nearly all of the top US brands (eg Now, Jarrow) do the same. Source the active ingredient from China/India, add fillers etc, assemble the pills in the US to get the "Made in USA" label) Regardless, is the efficacy of the product as advertised? Are they worth buying or mostly a scam?
I've found the products from bulksupplements.com to be legit for sure. On occasion, I've used their taurine and creatine. Now, as to the efficacy of certain supplements such as the ones you mentioned, that's up for debate. But I can say with confidence that if you buy from the place I just mentioned, at least you're getting what's indicated on the label.