Consider scrounging old car batteries. Even at a buck apiece, they're still a bargain. The so-called hazardous material inside is sulfuric acid. Treat it with caution like any other highly corrosive acid. Once a battery is drained, break the case open; Plenty of lead inside and most certainly a dollar's worth if you had to buy them from your neighbors.
Sulfuric acid is not what you should be worried about.
What you should be worried about are the trace elements present in and on the plates of the battery. Just a short list of some of the
dozens of toxic and/or highly poisonous things that you expose yourself (and your neighbors and family) to when melting lead-acid batteries:
Cadmium
Strontium
Arsenic
Zinc (the gaseous form of zinc is incredibly toxic)
And, heating residual sulfuric acid will release hydrogen, which forms ammonia, which then reacts with other trace elements to form such wonderful things as arsine and stibine gases -- gases so poisonous that the Nazis experimented with them in their execution chambers. (They only stopped because the 'rotten egg' smell was too strong and might have offended nearby villagers.)
I think Brian Williams summed it up best when the topic of smelting car batteries came up on The High Road:
Brian Williams:
Really, Really, Really, REALLY, stupid idea.
Dumb,
Idiotic,
Moronic,
Unsafe,
Bad,
Not Good,
Unsafe,
Poisonous,
Generally not a good idea.
In other words DON"T.
Plus....
Modern "Maintenance Free" and low maintenance batteries have very different plate designs than traditional lead-acid batteries. You essentially have to vaporize the lead in order to release it from the iron alloy plates, but there is no "hobby level" method for recapturing the (highly toxic) lead fumes, in order to put the element to use. It's just a waste of heat energy, a waste of your time, and a great way to poison yourself or your family.
Oh, and if you get caught doing it outside of an approved reclamation facility, it's a $20,000 minimum fine...