You obviously have a huge misconception between ceramic and carbon heaters. Good ceramic heaters are not cheap and I personally believe they are better than carbon. There are two ways carbon heaters are made; first a thin layer of carbon is sprayed directly onto a sheet of plastic. The second, carbon heaters are made by sandwiching a piece of carbon cloth between two pieces of plastic. If you like plastic in your sauna I would recommend carbon heaters.
There are three different kinds of ceramic heaters. This first are Ceramic/Metal Rod heaters, the heaters consist of a pencil thin metal rods that are coated with approx 1/2" of ceramic. You get approx 80% FIR (Far-Infrared-Sauna) emission from this heater. Ceramic/Metal Rod heaters are a good except the heat generated can be too hot. The second type of ceramic heaters are Aluminum Plate w/Ceramic coat, these heaters have a larger surface area than most, but because of this it cannot be made of solid ceramic or it will crack under its own weight, therefore a solid aluminum core is necessary. Since the majority of the heater is aluminum, the FIR (Far-Infrared-Sauna) emission is very low, about 15%. The last kind of ceramic heaters are Solid Ceramic Heaters which operate at 163 watts. Solid ceramics operate at a low wattage which will allow you to stay inside the sauna for a longer period of time allowing you to sweat more. The infrared wavelength emitted from these heaters 96% of its heat in FIR (Far-Infrared-Sauna) form and 80% to 85% in the 8-12 micron range which is the wavelength of infrared the human body emits. Remember as long as the wattage is below 200 watts on this heater, you get a highly therapeutic heater.
Two saunas which I am familiar with that use solid ceramic heaters are the TheraSauna and the Saunagen. Each uses the same 163 watt heaters. http://www.promolife.com
has a great sauna comparison page which will show you the differences with most of the heaters used. If you are thinking a purchasing a sauna it can be really helpful.