Hit the flea markets, swap meets, classified ads and yard sales for most of your purchasing. About the only thing you should pay full retail for is medical supplies. Most people do not have a well stocked first aid kit , let alone one in each car, at work and at home. I sleep better at night knowing my children each has a very loud, protective and territorial canine in their room. This is important, but brief.
Every good plan needs practice or it is no plan.
Things will go wrong. Things will be forgotten. At least once a year pretend you have a catastrophe and you are forced to live at home with no power, water pressure and the stores are closed. At least once a year pretend you have been forced to bug out with no warning and go camping. Practice skills like first aid and firearms handling on a regular basis.