There is plenty of ammunition available on line. You just have to know where to look. I buy all of my bulk ammunition on line.
Ammoman *
Palmetto State Armory
Cheaper Than Dirt (I know, I know
)
Lone Star Gun and Supply
MidwayUSA (I think this company might be pretty low on ammunition because everyone knows who they are)
Classic Firearms **
*
I have been an Ammoman customer for years.
**
I have been a Classic Firearms customer for a long time, too.
There are others. My FFL buddy and I were discussing this just last night and he was reading out of a catalog the various deals out there on ammunition.