You can build a traditional raised bed out of anything. There are no rules in my opinion (other than it being raised). Sure, you could buy one of those kits that does the seemingly hard work for you however there isn’t much to it. The location of your beds is an important factor but if in that tough corner of the garden, it can still or a difference.
I see the advantage of having raised beds as being three-fold. One: by having raised beds, you are less likely to be a victim of an early or late frost. Two: it’s easier to maintain and if you have back problems you might want to raise it to a height that is friendlier to work with. Three: it’s a great way to organize your garden and have some separation between different crops (that you’ll want to rotate to minimize the need for introducing fertilizers).
Most of my beds are fairly traditional and made from cedar but I’ve also repurposed a stock feed (think metal beer tubs you see at stampede parties) and several upcycled clawfoot tubs. Fortunately, both the stock feed and the tub comes with built-in drainage – plants don’t like being waterlogged.
As with many aspects of my garden I am also concerned about aesthetics. I wanted my plot to resemble a cottage garden more than a wartime garden – not to say there is anything wrong with the more militant approach, it still looks awesome (and who cares, you have near-free food on the table).