About snake's venom and its effects.

There are about 2400 species of snakes in the world, but only about 400 of them are poisonous.

A single injection of venom or a single bite is all that is needed to sensitise, so you definitely should not ask a doctor to test for sensitivity, as this may actually produce allergy. Also, sensitisation can occur at any time, not necessarily on the first bite/exposure, but potentially on a later exposure, as with bee stings. Thus, just because you have been exposed a few times without allergic reaction, does not mean that next time will be safe from allergy. The clear message is; try and avoid all direct exposure to venom (eg. bites, injection, breathing in milked venom etc). It is a good idea to always keep antivenom ready, but only if you have a strict rule not to try and use it yourself, because antivenom, though life-saving, can also have major, even fatal side effects and should not be used outside a medical environment.

There are thousands of venomous snakes in North America alone, many secretive, but look out for local herpetological societies, as a way of meeting other keepers. Also, consider making friends with the herp keepers at your local zoo. Anyone working with venoms, (those milking venoms, or venom researchers) will tell you that allergy to inhaled venom droplets is a real issue, often forcing them to stay away from direct contact with snakes after a few years. There are precautions you can take to reduce the risk, but not eliminate it. If your prime interest is in the snakes, not the venom, then it may be wiser to avoid milking altogether, as it may enable you to keep working with the snakes.

In regards to milking venom, this is a very specialised and expensive business. Increasingly, suppliers must comply with GMP standards to be able to sell product, requiring costly fit-out and operating procedures. I heard of one producer, who has had to spend around half a million dollars, just to add another shed for keeping snakes. It will take many years to pay this off. I suggest you contact some of the legitimate venom producers to ask their advice. As a starting point, try Venom Supplies their website is http://www.venomsupplies.com/

Toxicology.