My sewing room doubles as a guest room, so I need to make the most of the space. My solution was to buy an Ikea Hemnes trundle day bed (twin size but pulls out to be a full king). I got mine from the as-is section for 40% off, which made it about $200 for a very useful piece of furniture.
A hollow core door ($20 unfinished) fits perfectly on top of the side rails of the bed, making a large cutting table. For me, it's exactly the right height ergonomically for cutting, though I'm tall, so for some people this will be too high.
When the room is in quilting mode, I can store extra fabric, batting, and WIP on the bed, below the cutting surface.
When used as a bed, I stash the hollow core door in the closet -- it's very light weight and easy enough to move.
The bed also has full drawers underneath, which are still full functioning drawers when it's pulled out into king size. I use these drawers for fabric storage, of course.
Ikea bed doing dual purpose as a cutting table