The compost tea brewers come with enough compost and foods for 3 brews. Additional food kits are available.
I carry the same kits as Keep It Simple, but I've substituted a combination of high-quality composts (worm compost and conventional compost) that are produced locally.
You can also come up with your own compost tea recipe, but then you really need to get into testing it to make sure you make a good tea, so for most people, it's better to buy the kits that are proven to work.