If you have an old piece of plywood around, a new quality lazy susan could be screwed to the bottom at a considerable savings over the fancy ones.
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As a sometimes wood worker, I would suggest that you use hardboard,
since sometimes raw plywood bleeds. Not all, but any thing that ruins the
look of your carefully sewn quilts, etc, will drive you to madness!!!
Or, carefully sand the plywood down, several times till it is smooth enough
so that even a piece of panty hose dragged over it will not catch.
I wouldn't paint or stain it, that might open another can of worms!!