I could be wrong but I believe most anti-venom is now made through synthetic methods. Get a list of anti-venom suppliers from local hospitals and contact the anti-venom producers directly. Also try to get a list of venom suppliers. Milked venom still has other uses such as research. You will need permits and training in aseptic techniques etc. Most people are going to want to obtain their venom from certified labs or handlers. You will need to develop a professional relationship with your buyers. Another possibility is to be a subcontractor for another venom supplier.
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Randy Hallman
Firehouse Herps