I have learned that scrap yards pay good money for old car batteries. I stopped at a few auto shops and got 4, then stopped at a lake marina and found a few laying by the dumpster. I took them too. Scrap yard gave me $5 a battery. Made $40!!! Not bad when the driving was only 22 miles total for collecting batteries. I filled my tank and it cost me nothing. Gas was $4.23 for super (3.89 for regular!)