Cheap insulation. Is there such a thing?

Did not read all of the post so if this has been mentioned sorry......if it has a metal roof you will need to create a barrier of sorts to keep the hot air in the winter and cool air in the summer form reaching it......otherwise you will get condensation issues. Just stuffing insulation up against will not work to prevent this, all it takes is one very small air leak that allows the heated/cooled air to reach it and it will start dripping. Same with the sides except on the sides it will just saturate the insulation. Might end with a mold farm if you are not careful...