It is really easy and costs very little if you put your mind to the challenge of using the materials at hand. And it's like the look of something that may be a little different or even a talking point that will spark the interest of neighbors and friends.
Firstly understand that worms like to be kept cool and away from sunlight so finding an appropriate site will sometimes determine the size and look of the container. Also we do need to consider the wonderful worm juice, natures amazing organic fertilizer, that will result from the worm farm and what we want to do with it. I have placed a worm bin under kiwifruit vines with no rain cover over the top, only cardboard, and allowed the juices to flow over the ground and found the vines in that area to be particularly healthy, so collecting the worm juice may not be a priority if the site is a useful one and the area allows.
If farming on a small scale in a residential area then covered and concise housing may be best and one of the many commercially available worm bins are great for this as they are tidy and practical. However, if you are adventurous enough, and have a little bit of the inventor waiting to burst out, try looking at the leftovers around the neighborhood. All that is needed is a medium sized hardy container that can be insulated in winter should where you live get really cold.
My favorites are leftover tubs from renovations that are robust and hardy and don't take much work to set up. Old bathtubs are a bit too big for most of us so the concrete or stainless tubs are great. Old carpet works well as insulation and also as a food supply! Watch out for the possibility of carpet that may have been sprayed heavily for bugs and have residual chemicals that may upset the worms.
Set up the worm bin under some trees or bushes, in an unobtrusive place if desired, where it is shady and not too cold in winter and raise it so the juices can be collected if preferred and arrange a cover for the top. Again this can be porous or waterproof depending upon the level of rainfall and how concentrated the juice can be. A wooden frame and some roofing tiles look great. Make it readily accessible for adding kitchen compost scraps. Be flexible and try and make the bins blend in or even get the kids to paint them as a feature.
These "easy bins" as I term them, are not as straightforward as the plastic layered farms, with the resultant worm composting material, or worm castings, down at the bottom having to be periodically removed with a little effort, but they are an easy and cheap way to make a worm bin for home compost and it can also be fun!