I bought a used Emily's Garden and upgraded it a little and the whole thing cost about $60. Later, I made two different home made versions of the same thing for about $25 each. The air pump is the most expensive part. These set-ups held 6 plants. You could probably make something for 1 plant for under $15, that would give you a much higher yield, maybe 20 to 100 percent, than if you grew the same plant in dirt.

You can also buy set-ups that cost thousands, and everything in between.