These are exactly what I was looking for!  They are heavy and high quality.  The top part that holds the plant comes out so you can add rocks to the bottom for more weight if you live in a windy area, though I don't even think that is necessary!  The bottom part is also pre-drilled for drainage so you don't have to drill holes.  At the bottom of the insert, you can add a shelf for the "self-watering" part of the planter, or you can remove it if you're not looking for that feature.  There are so many options!  

On a side note, I did shop around in person at a bunch of different stores trying to find something like this.  They were significantly more expensive for this quality.  I highly recommend!!!