Unless you practice often or shoot a lot of guns, I wouldn't see the need for cases of ammunition. A few hundred rounds of practice or carry ammunition could do it.
Most of the gun ranges in my metro area mandate the use of store/range purchased rounds.
You could shoot a box or 2 but after that many places get huffy.
With the huge runs & industry delays, reloading & hand loading may become more common.
Some say these shortages are temporary but I could honestly see the dry spells lasting until late summer/fall 2013.