A) Almost all items sold to the public worldwide depend on a basic economic factor called, Supply and Demand. Right now at this point in time there is little supply and a big demand, therefore the market creates higher prices.
Ammunition manufacturers and importers are trying to keep up with demand. Most have increased production and the shortage should be over by end of March 2013 or at least stabilize. For the time being the panic buyers driven by President Obama's Anti Gun Campaign has caused severe shortages especially in the more popular military ammo calibers of .223; 7.62; 308; 9mm; and 45 acp.
Unless you have to have the ammo now, you should wait till supply catches up and the prices come back down. Even trying to get major caliber ammo anywhere in the USA is a problem because most suppliers and retailers are out of stock. If you buy now you will pay a premium price even at a Gun Show or online auction. Bulk ammo is still the way to purchase if you can find it at least in the five mostly desired calibers.
Important Safety Note - You should repack bulk ammo into 50 or 100 round plastic ammo boxes for safety reasons or store the lose ammo in a military metal ammo can. This means adding an additional cost for purchase so calculate that into the total purchase price. You may also have to pay S&H and sales tax depending on where you live.
Popular Military Type Ammo:
7.62 Bulk Ammo - Generally used in a AK47 style assault rifle:
.223 Bulk Ammo - Generally used in a AR15 style assault rifle:
308 Bulk Ammo - Generally used in a M-14 style assault rifle:
45 ACP Bulk Ammo - Generally used in an Uzi style assault rifle, or a military 1911 style semi auto 45 caliber handgun: