Six Drawers of Solid OAK base for storage.
Just push them together or apart for whatever your size bed.
$80 firm
I use a sheet of 3/4 inch plywood to span the base
and put mattress on top. I like a firm feel, so didn't bother
with box springs. For a extra $20, you can have the over-size plywood
and twin-size extra long (for adult) memory foam mattress.
This is currently in Lyons, but soon to be moved to Sublimity storage.