We have two Bounties and a Sprout. Here's how we are extending our growing without adding more Aerogarden units. This also allows us to grow larger plants like rosemary and holy basil (tulsi) in the pictures. We do this in several way. The picture of two used coffee containers shows one way. We drill a hole in the lid so the pod fits. We also drilled a hole for a 1/4" air hose and add an air stone attached to an air pump. For now we sit them close to the Aerogarden unit. We have found that the lights can be used to extend the growing area around the Aerogarden.
The Sprout we got free in a special offer when we bought one of the Bounties in in the picture as well.. We purchased the plate (don't remember the correct term) and can start 15 sponges. This works great for a floating hydro system we have in our cool garage (pictured) - the 2' x 2' tank holds 16 plants. We just love the Sprout - and of course our Bounties. With these add ons we can grow even more food and have a steady supply of veggies and herbs.
BTW - I started a tomato plant in an Aerogarden a month or so ago and transferred it to a 2 gallon bucket with aeration pump and air stones (2 sets). The plant is growing phenomenally fast. It doubled it's size in one week if you can believe that. I don't have a picture of that one yet.