I don't see the need for such purity unless there is evidence the other ingredients are harmfull. I see another bulk purchase is being offered by this Paul guy but with no guarantees you will get it and the price starts at $4 a gram. That is somewhat cheap but I've heard of lower prices being offered and you didn't have to buy any huge amounts. BAC is said to have a 50% res product and the price was very good.
The problem with the lower-purity plant extracts is that they invariably contain emodin. The amount can be as high as 20%, though 10% is more usual. Even a high-quality low-emodin extract, that is 50% resveratrol and 3% emodin (and this is very low) may have too much. Most have around 10% unless specified. A 500mg resveratrol dose will require one gram of the extract, and contain at least 30 mg of emodin. As little as 10 gm of emodin is a mild, but gentle, laxative. People vary somewhat in their tolerance, but I do not like this effect. Protykin ® is a 20% resveratrol extract, marketed commercially to supplement companies. It contains 10 to 20% emodin. Their approach is to claim emodin has health benefits -- which it does, as an anti-cancer treatment-- but in the doses we would be interested in the effect is not good. I took two 200 mg resveratrol doses of 20% resveratrol pills, 10% emodin, first in the morning and then at night, and woke up at 4 am with my bowels complaining. It was three days until I felt normal. I haven't had the nerve to try a 3% emodin extract. People vary; you may be lucky and be able to tolerate it. At the price BAC is selling, I think the emodin content is over 6%.
As for a commercially-sold 98% pure pill, it's not going to happen anytime soon in the good old US of A. Resveratrol is classified as an investigational drug, so the FDA have to seize any 98% pure pills if marketed for human consumption. Same goes for veterinary use. Technically they can seize any product claiming to contain resveratrol, but have so far chosen not to. They are treating the 50% and less extracts as an herb. I am told by a Washington lawyer that they are not likely at this time to go after small bulk purchases of pure resveratrol unless they find out it can harm people. Too few resources.
I think joint purchases by groups, such as Paul Wakfer is coordinating, are the best way to go as individuals; it's not illegal to buy or possess resveratrol, or to take it yourself. It's not a schedule I drug.