Garden Beds
Wicking Bed
I set this up a while ago (~2013?) and it has worked well.
Bed Material
Wood
These lasted quite a while, but I don't think I would do them again.
Brick
Dry stacked brick is what I currently (2020) have, it was quite a bit of work to get setup. The bricks I used were 8x4x2 and cost $0.37 each. I used 6 per side and 3 rows tall so 6*3*4=72 which comes out to $26.64 per bed.
Concrete
From this. I like that he leaves the pipe in. That simplifies things.
This is what I would like to do in the future. I didn't do it in 2020 because the set time is long. Cement is $4.10 / 0.6ft^3. If I make the garden walls 51x12x3 that's 1.0625ft^3. $7.26 per side $29 per bed. The extra cost is easily worth the effort to not have to work with the dry stacked bricks. I could add a core of rigid insulation to make the form lighter. It would add a very small amount of cost, but again, worth it. Particularly because without it each side is going to weigh over 100lbs.
Perlite or vermiculite can also be added, but those are more expensive. See here.
Adding a dark dye could be a good idea. While it might make them look better, it will absorb more sunlight allowing them to heat up sooner in the spring.