Personally, I think 10,000 rounds on hand is a good start. Most of that is for the semi-automatic firearms I keep, the rest I divy up amongst the more traditional hunting guns.

A reloading setup can be a handy thing to have when the bubble goes up as well. You can make up handloads that you could not easily duplicate on the open market. Casting your own bullets gets even better.
_________________________
The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)