Easier to store than you think - you don't need a warehouse, garage or anything - under bed storage, nooks & crannies in the closet, etc. can all be good places to squirrel away things. You can get bottled water, some canned goods and energy bars, on a budget, you can add a little bit to each trip to the grocery store to have a contingency stash... old soda bottles can be cleaned and filled with tap water for an emergency (there are all sorts of cheap and free prep ideas online).
I'm good for about 1.5 months (2 adults, 2 children) - I went through our pantries yesterday and casually told my wife we need to get to the 2 month threshold - she cheerfully agreed. We've got a good stock of canned goods and gear, but need to add more dry goods to the mix (beans, rice, oatmeal, etc.). Also, for Christmas, I'm planning on getting a food saver and food dehydrator for the family.
1 area people often neglect is water - a $20 waterbob is a great investment - basically a 200gallon bladder that sits in your bathtub - stores the water clean (from the tap) and keeps it from getting funky. Weighs about 1.5 pounds, we store ours in the cabinet under the sink in the bathroom. CheaperThanDirt also has a gravity filter kit - just need 2 containers and a drill to make a gravity filter good for hundreds of gallons. You can also pick up a pump filter for emergency duty. Of course there is always the option to boil or use purification tablets, or even bleach. I've had bleach-treated as well as iodine-treated water... tastes lousy. They are a backup for me over filtered options.
Try to keep preps in 4 categories:
1) Home emergency [short-term] (power outage, hurricane, etc.) - consumable supply based
2) Homestanding/homesteading [long term] - ability to process food/water
3) Transportable [vehicle] - may be quite limited
4) Carriage [person-packable] - very limited
Just my $.02