A really cheap source of sulfuric acid is at pool supply stores. It's the acid they use to balance the ph in swimming pools. In other words if you swim in a pool you are swimming in some very dilute acid. In California the last time I bought the acid, it cost me $5 for 2 one gallon jugs. That was in 1999. All you have to do if you want to make sure that it is nuetralized before you dump it is put baking soda in it until it stops fizzing. That was all that was required by law in California before we dumped our acid solutions down the drain after using them in the pickling process for jewelry.