[Christ]

For every $21 you spend, on cores, you get the opportunity to make $31 - extend your expenditures to include another core, and pocket the $3 extra.

Do it often enough, and you'll find that you're able to make a decent recreational paycheck off just the used batteries.

PS - the sulfuric acid in batteries doesn't dissipate... if you can find a use for it, you can usually drain them, boil off the water, and get 80% clean sulfuric. I used to have small drums of it from recycling batteries, and had a company that would buy it from me for $20 per drum. It took forever to fill a drum (they're 7 gallon... more like carboys.), but $20 more was good enough for me when I was using the (wasted) heat from a garbage fire to burn off the water. Lead/acid sludge is really hard to get rid of, though, so I usually just turn them in whole now.