I started just like most every one else wanting to do a raised bed garden, but the cost was more than what I wanted to invest. Prices ranged from 40 to 120 dollars for prefab kits and buying the raw materials to build a raised bed was still 20 dollars or more with out buying the dirt to fill them in. It dawned on me one day driving to work seeing these blue cattle mineral feed buckets why not use those. So I contacted the farmer and he supplied me 100s of them free of charge. He explained when purchasing the feed most have a 5 to 7 dollar deposit but in the quantities he takes they do not charge the deposit. It was beneficial to him to give them away so he didn't have to haul them away.
I am now on my 7th year using these buckets and so far they are holding up well and I have discovered tricks along the way to maintain my garden more effective and efficiently. Making a water reservoir simply by drilling your drainage holes on the sides instead of bottom will save time watering. Adding some limestone gravel in your bottom layers of soil will keep a steady supply of calcium and magnesium for your plants. Weather it be in containers or a raised bed nutrients will need to be replaced. Worm castings and compost through out season will help tremendously. This has been the cheapest and easiest way I have found to have a back yard garden. 
