I'm going to assume that this post is a troll but none-the-less...
1) there is an EXTREMELY limited market for venom and that market is by and large supplied by people who are already in the business (I suggest an article from Reptiles Magazine about Jim Harrisons venom lab in Kentucky if you want to do some background reading)
2)venom used for antivenin(om) must be extracted/processed/stored in laboratory conditions, setting up a lab suitable for this in all likelyhood would run in the tens if not hundreds of thousands of dollars
3) if you have a genuine love for keeping and working with hot snakes the LAST thing you want to do is milk them. This is an extremely stressful and risky process which should only be done on the basis of absolute necessity... snakes will often go off food when restrained and subjected to the stresses of milking (or force feeding or anything else necessitating head restraint)
4)lastly (and again I'm assuming this post is a troll) being bitten by spiders shows a lack of caution and common sense which defies description. I know individuals with literally thousands of spiders who have never been bitten and spiders do not (generally, with the possible exception of pheuneutria spp.) pose anywhere near the husbandry challenges associated with working with many venomous snakes (if the spiders to which you refered were not part of a private collection ignore this last part
If the vast wealth of experience which the other individuals on this forum impart still can't disuade you, before even considering undertaking a process which requires direct physical contact with venomous snakes try to find someone experienced who can let you at least work venomous snakes in a supervised environment.
The reason we all try to disuade people from keeping these animals is that everytime someone chooses to and gets hurt it jeopardizes all of us who've been doing it for a while by way of greater restrictions or stricter enforcement of preexisting laws. If we all try to talk someone out of keeping hot snakes, and they do it anyway....well its there life and either they can cut it or they can't....but at least by evaluating their reasons for keeping these animals and, in there own head, dealing with the counter arguments we raised they'll (hopefully) be better prepared to deal with the challenges these animals present which we've already had to deal with.