In this video I'll show you how to build a wicking bed. It's like a giant selfwatering pot that keeps the roots out, grows a great garden and is a brilliant water saver. There's stepbystep instructions on how to make one out of these commercially available IBC (bulk containers). Make sure you get one that has not had anything toxic in it before it's come to you.
I do think there are cheaper ways to make this that filling the IBC with scoria you can use besser blocks, some wire mesh.. basically anything that separates and hold up the soil from the water, and wont contaminate the water.
This is for you if you want to make a waterefficient garden especially if space is tight, water is scarce and you don't want to muck about watering everyday in hot weather. This same technique can be used for any container. Just remember the basics of getting the layers right, not to have soil sitting in water and grow what you want.
It's a bit of effort to make but you will reap the rewards once it's done it works a treat
Cost: Once you've seen what I've done here you'll see ways to cut cost and corners. You can use recycled material, different rocks, not as many fancy fittings etc.