A transferable minigun about $200K. Ammo at a slight additional cost. Of course, you really want the Dillon Aero Chevy Suburban with the minigun. But sales are restricted to "special" government agencies.
Here's my back-of-the-closet bailout bag. I keep a similar one in my truck, minus the S&W M1917. It once belonged to my great-uncle, and followed him home after WW1.
Aside from a sheath knife, the kit has four different flashlights and batteries, several forms of fire starters (a Bic disposable is you best primary choice), and first aid supplies. Be sure you have a supply of prescription items to last a week or two. You can never have too many sources of fire and light.
You should also consider your computer when building a survival kits. I have my key financial and personal data backed up on an encrypted USB drive, which I carry with me. Less-frequently-backed-up data also resides on thumb drives.
A future project is to build a bootable Windows XP on a 4GB USB drive. That way, I can take an operating system, key apps, and my data with me, even if all my hardware is lost.