everyone wants self-priming, heat tollerant pump, but no one wants to pay for one. you simply can not get a self priming impeller-type pump that will work for hot beer (the impeller pumps that are self priming use a fluid resevoir, which you dont want for food). impeller type pumps are the cheapest because they have very few parts.
you can get a peristaltic pump, which several people use, but those are $$ and the flow rates arent as high. or you have to make your own, which has been done.
the next best thing would be a diaphragm pump. those have considerably lower flow rates but higher head pressures, and are just as expensive.
CO2 for transfering isnt going to work because your boil kettle isnt air tight. and you will be contributing to global warming by exhausting all that CO2, and wasting money.
just make your life easy and buy a march pump, and just be aware of its limitations.