Kind of interesting you mention this. I remember the last ammo "shortage" and talking to the people in the sporting goods section of my local wally worlds. According to them they weren't having any particular problem getting in ammunition, it was just when they did the LGS owners would be waiting and buy it all up, creating shortages at the wally worlds which were the biggest sources of local cheap ammo.
My biggest problem is controlling my patience. Waiting is not one of my stronger points, and I have enough parts on hand to do at least one complete lower, purchased prior to The Madness. I saw today my LGS has some bushmaster uppers in stock, but at about $780 a pop. Not stellar pricing by any stretch, but I know they won't last either, so therein lies my dilemma. Wait and twitch till prices come down and availability goes up. or satisfy my craving now and pay the premium.