I bought one when they first came over from Classic Firearms. It came with the armory book. Wasn't shot much. Just inspected ever so often. Can't remember what I paid for it but was way after people were getting them for $150. I want to say I paid like $400. First thing I did was chop off the useless bayonet assy and replaced the grenade launcher with a flash suppressor. Then the stock was too heavy because the cosmoline was all the way in it so I dumped it for a conventional Choate stock. But the biggest rat hole I went down was it was popping primers in modern steel case ammo so had Murray do a $75 throat job on it. But it shoots good now in as much it passes the Russian instructions for inspecting and zeroing an SKS. It was built in the early 70s. Don't remember the exact date. I want to say 1973.
$400 + is the going rate for a sks. That's just reality. The cosmoline job SUCKs so unless you get it for a song or know it's some mint/rare variant...spend the money on one already cleaned up. You can get a nice Russian for around $600.
$400 + or - $50 either way is the going rate these days. They are still for the most part pretty inexpensive but it's crazy how much they've gone up over the years.
A Norinco SKS was the first gun I ever bought myself, $180 on my 18th birthday in early 2001. Still shoot it. I got a Yugo for $420 basically unfired 2 years ago and it’s pretty damn heavy and unwieldy by comparison. Things have changed a lot but I guess keeping inflation in mind they haven’t shot up THAT much.