what ive learned from some hippies out west, they are making there own compost tea, and they aerate the water with a air stone and feed it to there lawns after about 24 hours of brewing, the results putt name brand stuff to shame.
here is a web site with some small info on this
just google compost tea for my lawn
and this ones more in detail
and this one
you get the point for under a 100 you could have the stuff to do it yourself monthly