Around here almost everybody has steel panel doors and I can't afford the fancy ones. They are really expensive compared to my redneck insulation job.
Finishing insulating my shop was the best thing I ever did. The previous owner insulated and sheeted the walls with OSB, installed an insulated garage door, but left the ceiling open to the roof decking. I put some OSB on the lower cord of the trusses and blew in some cellulose. The previous owner also installed a wood stove but never lit a fire in it...ever. When I inspected the chimney there wasn't any trace of a fire ever being lit. I had a brand new 20 year old cast iron stove. Some people...
My next project is to put foam up in the ceiling between the rafters. It's gonna take a looooooong time but I'm gonna get there eventually. It's a block garage and needs to be tuck pointed BAD! That should help tremendously too.