I'm an enthusiast handloader, so the truth is that I don't buy a lot of ammo. With that said however, I have still bought sizable lots of rimfire, handgun defense ammo and also 5.56 ammo for AR's as I don't care for the workload related to feeding AR's.
So I've bought ammo in a group buy with buddies a few times. SGAmmo, Target Sports and Outdoor Limited have all given me great prices and great service every time.
We have been through moments, politically motivated, where ammo was a damn difficult subject. Currently we are experiencing the OPPOSITE and ammo prices are as fine a deal as they have been in years.
I love the suggestion to buy right now and then if something spicy drops on a Black Friday (or cyber Monday) deal, buy some then also.