Ashwagandha Root Extract vs Powder
The recommended dosage of ashwagandha depends on the type of supplement. Extracts are more effective than crude ashwagandha root or leaf powder. Remember to follow instructions on labels. Standardized root extract is commonly taken in 450–500-mg capsules once or twice daily.
The cheap ebay source might be low quality, contain contaminants or mold. Very few bulk ebay sellers bother to test before reselling.
Undersun have excellent staff and lab equipment for doing quality assurance and analysis. Why bother with cheap stuff on ebay?
The raw root powder has about 0.2 percent withanolides. Sensoril brand extract is the strongest on the market with 8 percent withanolides, thus 40X extract. NOW brand is 2.5 percent withanolides, thus 12.5X extract.
Jarrow sells Sensoril brand extract, in 120 225mg vegetarian capsules, which costs $10.92 on Amazon with Subscribe & Save if you're in the US. One bottle should contain the same withanolide content of approximately 1080 grams raw powder. Basically Jarrow brand bought at Amazon costs about $1 for the withanolide content of 100g raw powder. Now brand costs about $2/100g equivalent. Your eBay source is about $4.80 per 100g raw powder (plus shipping). So for withanolides only, the extracts would appear to be far more economical.
Keep in mind, Sensoril is an extract from root & leaves. Also several published studies were done with Sensoril. I suggest trying an extract and raw powder and seeing which works better for you.