You're the type of "hoarder" that ammo manufacturers love. Buying ONE box of 1,000rnds would save you a TON of money, but for whatever reason you'd rather pay the packaging premium on each box, one at a time. Volume discounts are a good thing.

And for the record, you're not an ammo hoarder yet. Having 500-1000rnds for someone that shoots semiauto's on any regular basis is not uncommon. My fiancee and I usually hit our handgun range (private) 3-4 times a month with 4-5 guns in tow. It's not uncommon for the two of us to run through 300-500rnds each trip. I reload in 1,000 and 2,000rnd batches. If I buy factory ammo, I almost exclusively buy cases. I usually buy my brass, bullets, and primers in 10,000 count cases.

I'm not sure what to say about your "zombie invasion" theories, it frankly worries me that you own a gun and even comment on "zombies", but in the event of an "armageddon" scenario (or zombies I guess), 1,000rnds won't last very long if you need to defend yourself, feed yourself, and will have no access to a fresh ammo supply, let alone if you were to plan on any sort of "offensive action", like invading the neighbors to take over their supplies...

But then again, I'm not personally very concerned about any impending zombie invasion...