A few years ago I bought plans to make the Mini-Microbulator compost tea brewer from Tim Wilson's site It is not difficult to built and the PVC piping parts are not expensive. You only have to find a suitable air pump.
A YouTube video of the brewer:
If I had asked people what they wanted, they would have said faster horses - Henry Ford. Tiny ad:
It's a bit like "run away to the circus" but for gardeners