LOVE workboxes! Here’s a picture of ours. Workboxes really streamlined things for us. I got these drawers at staples years ago, no stability problems and they can hold a heavy textbook (think Apologia high school science books!) I liked that I could add on drawers fairly easily. The drawers aren’t easily removable by kids though–which may be a pro or con!
One thing I found when looking at stackable drawers–ones with corner supports are more sturdy than ones with side supports. So, look for corner supports.
Here’s a description and more pictures.