@buffy2011brought to my attention that Walmart has a 1 qt heated water bowl on sale for $10.63 http://www.walmart.com/ip/Farm-Innovators-Heated-Pet-Bowl-1-Quart-Blue-Dogs-Birds/14660238 I have never seen one so cheap. If you feed ferals over the winter and have an electrical outlet, these keep the water from freezing. I have never seen one for less than $30.