A green house is a great idea. And you can build them for pretty cheap to. I recommend checking out this book on how to build them. It has everything you need to get started.
For the very best results I would recommend you look at a clone machine. The clone king brand is what we use however I would search around as prices can very. I paid $60 for 1 but i have seen a lot of fake ads for $500. Any cloning machine would work and you can build your own.