Take a look at target sports as well...much of their ammo includes shipping, which can really add up.
I am a big fan of vendors that include shipping into the price.
I used to be a snob and never shoot steel cased ammo. I am always after precision in my rifles, but I will use steel cased ammo for training purposes. The Hornady Steel Match is good steel cased ammo. I also use Wolf steel cased as well. The only steel cased ammo I'd avoid is Tula...it seems to be the dirtiest and underpowered ammo.
I like buying from The Amory as well since they are in VA. Shipping isn't included, but shipping isn't too expensive and quick delivery.
I like Ultramax 55gr FMJ re-manufactured .223 ammo and have been shooting it for years. All loaded in Lake City cases. Now and then I get lucky and find their 150 packs on sale. Years ago it was around $35, now closer to $70 when not on sale.
At one time I had an AR, Mini 14, H&R single barrel and a M700. Ultramax stuff shot very well in all of them. Keep a few 150 round packs around, for "whatever comes up".
Natchez and a few local places like Trop's, Dick's, Field and Stream, sometimes have bulk ammo, but it's not all that "cheap" these days. I prefer LC or Federal M193 for my AR now.
Was often getting thousand round batches some years ago for less than 20 cents a round. About fifteen years ago, some of the best stuff around in milsurp 5.56, was Malaysian M193 that cost maybe 18 cents a round. Wish I had bought a few more 1K cans of that. Those days are gone, sadly.
I shot a fair amount of the Israeli IMI M193 and it went bang every time and accuracy was just like other 193. I never shot it over a chrono, but was always told it was the hottest of the M193 ammo. I never shot any of the Turk stuff.