I love dairy crates! Many people wouldn't keep them as furniture but I keep a few around.
They can be stacked upright for storage or sideways as shelves, and you can sit on them.
They're often discarded so no need to spend any money.
If space is an issue, you could forego a mattress. I got rid of my mattress almost 5 years ago and sleep on a mat. I pick it up and store it in the closet every morning. This isn't comfortable for everyone but the extra space is so valuable for me.


