Freon is a Dupont trademarked name for refrigerants they manufacture. So if it's got Freon on the can then it's a Dupont product only. I would think the only difference in quality from manufacturer to manufacturer would be how well they control impurities in the material and I don't think that there would be any way for the general public to assess that. I wouldn't worry about it and buy what is available, the manufacturers typically make huge quanitites that are repackaged into the smaller 2 lb cans we are all familiar with. I don't think you could find out who made if you wanted to.
If you are talking about the differences between R-12, R-134, R-406, etc. and their relative costs then cost is not what makes it work. Each type of refrigerant has very unique and has different characteristics that the system they are used in has to be desiged for. R-12 was the refrigerant of choice for autos up into the 80's. It was phased out because of it's ozone depleting charateristics and has not been made by anyone for years. Any that you find to buy is stuff that was stock piled and the price typically reflects that. R-134 is the current refrigerant of choice for autos. R-134 does not work as well in an old R-12 system and you have to be careful about the compressor lubricating oil or you will plug up the system. Real old hoses and seals will leak with R-134 too. There are some blends out there that are supposed to work nearly as well as R-12 in an R-12 system and are compatable with the oils used but those will cost more if you can find them.