Alumalite came from a guy that puts up and takes down signs. When he takes them down, they are no longer needed and he sells them for $10 a sheet. He advertises on Craigslist when he has a bunch gathered up (every couple months). I would guess that you can contact local sign shops and ask if they have any for cheap that you can buy. You can even peel off the vynal that they print with if you take the time.
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