It might be a bit urban, but vertical gardens have become popular in the last couple of years, but I especially love the idea of using discarded pallets. No need for the designer price tag, when you can make it yourself.
I think this is an achievable project for most people, and it would be even more economical if you used seeds, rather than seedlings. Just more patience needed, and maybe some extra patience to 'find' the pallet.
You can find the instructions for this project at Life on a Balcony.