We like our cover, seems to help with extra insulation, especially when you don't have a canopy up and the fridge is in full sun. We bought ours at American RV for 40 something.
But note that the picture displayed there doesn't look like the one I have. The one I actually received works, it's just that it has zippers and not the velcro top closures that the picture displays. So you may want to check that whatever you will be receiving will actually be what you think it is.