ok, what about a rock river
theres nothing wrong with direct impingement. you dont even need scrub your gas tube, etc. keep your bolt clean and oiled (not hard) and you are set for reliable firing.
That's the thing that really annoys me about those Keltec SU model .223 rifles. I REALLY wish they would make one at a similar price point, that consisted of the same basic operating mechanisms and components BUT, in more of an AR layout with a pistol grip, stock, etc. It would be a nice and inexpensive alternative in .223 for avoiding the crappy direct impingement system of AR's....for someone lazy like myself that doesn't want to deal with cleaning a DI system.
For cheapo .223 alternatives to the AR there is also Mini 14's and the newer production AR-180B's (I think that's the proper nomenclature). Most of those you can usually find at least a few in the $500-700 range sometimes.