I also use wrapping paper, scrapbook paper, tissue paper, whatever I can find to enhance the look of the cake. Then cover it in clear contact paper. All of my cakes are on a cardboard rounds so they dont come in contact with the board. Ive also covered boards in fondant and sometimes use an impression mat. My dh cuts plywood boards for me. My problem is that he cut a bunch that were pretty big compared the size of my cakes. Then I couldnt get him to re-cut before I needed to use them. So a lot of my boards look huge in comparison to my cakes. But I still think it looks a lot better than plain cardboard or foil.
I bought a big roll of clear contact paper at the dollar store and I always have remnants of wrapping paper and tissue paper to choose from so the cost is minimal. Yes it does take a little more time, but if I'm going to spend my time making the cake look as good as possible, I may as well spend a little extra time on the board. That said, I'm a hobby baker. But honestly, I think I would do it even if it was a business for me.