I just paid $185 for a basic used carbine. I know I probably paid too much but I've been looking for a great deal for a couple years now, so the day after Newtown I happened to find one and snapped it up. I looked up the SN and it was made in 97 I think.
This thing was all stock, bare bones and very dirty. I installed an auto bolt release and recoil buffer, and am waiting on a mag release. When I picked it up I also grabbed a 25 round Ruger mag and have been kicking myself ever since that I didn't get 2 or 3 of them, there are none to be found anywhere near here right now.
I have a decent scope installed and am waiting for a break in the weather to coincide with a break in my schedule so I can shoot it some more. So far I've put a few hundred through it without any issues.