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:
Let's get him boys! We'll make him read this tiny ad!
Quit your workee-job and live, year round, for free-ish in Montana