HomeDepot does carry Garage Door Insulation Kits. They are made by the Insulfoam division of Premier Industries, Inc. They sell of about $40. The problem is they only fit 8' doors. If you have a wider door, you have to cut up two kits to do the job.
By the way, my experience with asking question at HomeDepot has always been met with a courtious "I don't know" or "we don't carry those." The first was correct and the second was not.