I thought about this quite considerably a few years back. Bought jerry cans, water drums, canned goods, seeds, etc.
I've got plans to head outta town to a mates property in the back of bumfuck. Fortify, load up, plant up, smoke up :D
That is of course in the event of non catastrophic doomsday scenario. In the event of total worldwide destruction. I'd appreciate a quick one in the ear to save being horribly tortured by radiation poisioning. (cosmic or manmade)