Sheesh, you'd think we'd have a sticky by now which discusses everyone's luck with various brands of ammo. It'd be great to see the failure rate attributed to various ammo in a poll which prospective newbies can just refer to.
Short and skinny: Wolf is cheapest, but also not the most accurate. It's possible it may not run well in *your* AR, so buy 1 couple of boxes and find out. Use it for plinking, and get M193-spec ammo for serious work.
Winchester Q3131A can usually be found for $170-180 at gunshows, and LC XM193 for a little more. Sportsman's guide has the case of LC for $180. Anything less than $3.50/box of 20 for M193 is generally acceptable, but you have to catch it on sale for it to be much cheaper. South African Battlepacks are M193 spec, but those are 20 years old and not as accurate, but pretty darn cheap. Availability is poor; Sportsman's Guide already sold out of the preorders. Like Charging Handle said - let's hope more comes ashore.
I keep a stash of Q3131A and XM193, and plink with Russkie ammo. If I ever have a malfunction with the ComBloc ammo, I'll reevaluate based on the severity of the failure.