With Grape Seed extract it is hard to say. There are patented forms like Mega BP (extract, 90% polyphenols), but you can also buy extract in bulk dirt cheap -
for example from bulkpowders.co.uk and cap it yourself, which is what I do.
Also, there's conflicting information on the right dose and if Bioperine helps absorbtion or not.
You should check examine.com's info on GSE, and judge for youself.
According to their information, the low bioavailability makes many of the effects seen in studies hard to achieve through oral administartion - making GSE look a bit overhyped and overmarketed at least regarding the standard 300mg dose that most supplements use...
In the end, you probably would do best in first ordering one of the more expensive brand extracts from a reputable brand, and then buy it cheap in bulk afterwards to compare effects - it's the only way to know for sure.
Edited by chris106, 04 May 2014 - 09:43 AM.