Same thing here in California. We have a bill being proposed that will require a DOJ $50.00 extortion fee for an "ammo buying permit". Each time you buy ammo will require a background check, just like a gun purchase. It will ban Internet ammo sales. If you buy more than a pre-determined amount of ammunition at once, your local law enforcement is notified.
Depending on what the "pre-determined amount" is, the police are going to get very tired of the notifications very quickly. It's not as if they can actually investigate anything based on the reports, since the mere fact that you bought ammo doesn't give them a basis for a search warrant. At most, the police could call the buyer or stop by to ask if he has any nefarious plans for the ammo, but the buyer doesn't have to take their call or answer the door.