You can buy the 97% version. Then a quick analysis (IR specter, NMR) will give you an idea of the contaminants if they are not specified by the manufacturer. Based on that you can take additional step to purify the product (extraction, chromatography, etc.) to the required level. The yield may not be perfect making overall cost a little bit higher, but this is really basic organic chemistry.
How do you get from 60% to 99%? Do you have to (for pharmaceutical grade)?
What are the remaining 40%? poison? harmless byproducts?