“ Surely one can piece together or buy a reliable AR for under $1k even in these times.”

But to answer this question, yes you can and I did.
I found a Daniel Defense 14.5” mid length barrel. These are gassed right and have minimal dwell time so they shoot very soft. I put Magpul SL hand guards on it cause I like utility. Bought an Aero upper, lower and LPK. Bought a Colt RE along with their castle nut and end plate. Magpul grip and stock, DD A1.5 rear sight cause I like them. I did splurge on a Geissele trigger but I already had it.

Oh and it shoots really well