If you are handy with woodworking I found this site to make screened bottom boards. I went to Highland hardware and got a roll of screen for about $20. This roll looks like it will make 100 screened bottom boards. Using scrap wood these were easy to make. Other than the screen, there was not cost. You will need 2 scrap 2 ft. 2×4′s . On cold snowy days this was easy breezy. the web site is
http://www.myoldtools.com/Bees/bottomboard/bottomboard.htm
wow… thanks a million for this!
Now i can make an even cheaper bottom board.
I figured (buying the wood @ lowes)… I can make one of these for aprox $4.11