I am pretty new here myself, but yes you are right about the bleach. 6% is chlorine and the rest is water. Or at least that is what you hope for.

$4 a gallon for 6% generic at Wal-Mart
Holy smokes, where do you live? I can get generic 6% bleach for $1.50-1.75 at the grocery store or walmart or dollar store. Even Clorox doesn't cost but $2.50. But where I live the pool store is asking $7.99 for 12% chlorine! So you can see what I choose to do. I guess it just depends on your pool store prices...it may be cheaper for you to get it from them.