We lived in a two bedroom high rise condo. The second bedroom was small, so we had a murphy bed built and installed.
We didn't cheap out on the mattress or box support. The box support wasn't spring but rather a slat support. It was very comfortable. When it was stowed, the "wall" portion had a drop down table built into it; very convenient and usefull. A desk was built into the corner where my PC sat. We have since moved to a house with ample room, but I would do it again if required.
I found the web site of the place we bought from. It's local here but it should give you ideas of what to look for.
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