It's cheaper to build your own. For four plants you can do a bubbler $10 Walmart duo line airpump or ebb and flow pond pump submersible $30 Home depot. This is all plants in one large tub. How large are you planning on growing these plants? Larger than a foot tall you many need to separate into bigger containers.

For four plants dirt is really easier for beginners. You'll be spending enough money on lights and fans and nutrients and coolers and dehumidifiers. Get my point?