Although some other companies don’t seem to share our view, we see no point in selling low-res textures. And we consider everything up to 1024px x 1024px as low-res.
We provide these low-res versions of our textures under a Creative Commons Licence (CC BY, details here), which even allows for commercial use. You may use them in any way you wish, as well as for any purpose. If you find yourself using such textures regularly in your professional work, please consider bying a full licence – we would appreciate it!