http://en.wikipedia.org/wiki/Astragalus

Found the extraction of Cycloastragenol on Amazon:
http://www.amazon.com/Cycloastragenol-50mg...t/dp/B007NIYSI2
An annual supply costs $3480...

Oral consumption may be ineffective: http://www.ncbi.nlm.nih.gov/pubmed/20877137