Thanks for the input. I wanted to get some opinions of them, before I mentioned that I went ahead and bought it.
It was right at the last aisle of the show, at a table with a couple used AR's sitting there. The guy behind the table clearly didn't know much about AR's; he was more interested in reading some paperback book. When I tried to explain to him that I was really just looking for a used, private-party-sale, lower receiver to build a new carbine, he dug around under the table for a few seconds, pulled this out & said, "Would that work?" It was a complete, assembled lower, with all internals, as well as a tele-stock. Looks absolutely new, no wear marks on even the internal surface areas that get scuffed by just the first few rounds thru a gun. It was exactly what I was looking for, except for being new. I really wanted a private-party (i.e., paperless, yet still legal) sale.
Anyway, when he brought it out, it caught me off-guard enough that I automatically asked "How much?", even though I wanted a used one. He seemed embarrassed to be asking money for "just part of a gun" (his words

), and said "Two hundred OK?" Naturally, the response was "Ubetcha", even though I didn't want a new, papered receiver.
I pull out my wallet & hand him 2 hundred-dollar bills, figuring if he doesn't mention tax, I wouldn't, either. So he takes the money, and just says "thanks" and sat down. Expecting a 4473 needed to be filled out, I asked, "Is that it; are we good?". He said, "Yep, thanks" and went back to his book, so it turns out it was a private-party sale after all. (If he's a dealer, which I have no way of knowing, the responsibility for getting paperwork filled out is his, not mine. If he's not a dealer, there is no responsibility for paperwork on either of us. Either way, I did everything I was supposed to do, so I'm good to go with it; so I just went home with my unfired, private-party-sale CAR-15 lower assembly.)
This lower doesn't have the mark I've read about on the front of the magwell, that Eagle arms sometimes has, that's supposedly somehow related to government inspections for government-purchased Eagle Arms weapons; just the eagle emblem and Armalite logo on the left side. I don't know if that means it's an older one, a newer one, or what.
Maybe time will have to tell; I couldn't pass up that price for a new, assembled complete lower with telestock already installed.
I put a couple mags of .22lrs and a half-magazine of .223's through it last night, with no hiccups. Keeping my fingers crossed...
To complete the build, I called ArmsTech this morning about their progressive-gain, polygonal-rifling AR uppers, as they generally give velocities equivalent to a 50% longer barrel; i.e., their 9.5" SBR upper gives the same velocity with the same ammo as a normal 14.5" M4 upper. So a 16" version should give velocities roughly equivalent to a 22-24" AR barrel. Unfortunately, they only make LE and Class 3 stuff, nothing civilian-legal length (they said it'd be at least a year), and I want to keep this a completely civilian-legal rifle, so no Arms Tech upper for me.
I figure to order a new lightweight CAR upper for it this week out of Shotgun News (or possibly off AR15.com), and put AAC's flash hider on it, so it can use the AAC suppressor.
This is fun.
