I bought one last year from classic firearms for $185 + tax/ship/ffl fee. It was the bog standard, most common variant (minimal cool quirks) and also the only one in stock. I'm happy with it.
It is stamped 1943 and all 4 serial numbers (incl. bayonet) match. It spent last few decades in a Ukrainian arsenal (based on stock marking) and was eventually exported to US and sold by CF.
I had to clean the cosmo, it wasn't "covered in it" but you could definitely see the yellow tint on working surfaces. I just disassembled the bolt and put it in a big cheap pot, submerged with water, and boiled for a few minutes. This made a stink but it went away after 1-2 days. The cosmoline bubbled up to the top. I then fished out and dried the parts. The barrel I took out of the stock and left in the summer sun. Cosmoline dripped out. Remaining trace cosmo was removed by wiping with turpentine. First time I did a very poor job (first time ever cleaning cosmo) so I'd get sticky bolt every 10 rounds. I wiped with turpentine again and it was fine. The stock still sweats some cosmo after getting hot.
Rifle seemed zeroed already, at least 90% of deviation seemed to be due to my technique, which will probably take me years of practice to correct. It seems reasonably accurate, and I can see it being effective at up to 200 yrd. Supposedly these are good up to 700 m, but for that you need to get one of the snipers or other very good ones, which cost like $500+ (probably need to buy several too), and you have to be really good. Otherwise you ain't hitting shit.
I get sticky bolt after about 60 rounds over 1 hour. I hear that this is pretty average. That's about when I end my session anyway.
I had to buy a bunch of accessories:
>recoil pad because the metal butt plate bruised the hell out of my shoulder (seemed about as painful as 1600 fps 12 ga slugs)
>set of tools mainly for the headspace gauge
>clips
>single piece cleaning rod because my collapsible one was too short
The ammo is indeed cheap, but as I say above between the harsh recoil, heat (barrel gets very hot if you shoot fast and causes sticky bolt), inevitable sticky bolt after ~60 rds, I don't actually fire in large enough volume for ammo price to matter. My current ammo is brass case PPI at $0.7/rd, the really cheap ammo tends to have nasty shit like lacquer and requires a lot more cleaning. You kind of don't save enough money to justify the extra work.
It's a pretty neat rifle. Fun to shoot (although it's very rugged and basic, you can see the bolt move as you pull the trigger lmao) and play with. I like the fact that it's kind of a USSR artifact. Pretty heavy, and quite long too. I do want to try taking it deer hunting but I have a feeling it will be exhausting to lug it around. Not that expensive, but hardly "cheap" at >$100 especially considering the accessories you'll end up getting. At today's price in purely practical terms you can get better rifles, it's a decent rifle but there are better ones now. The nugget makes sense if you like the history and so on.
I would recommend getting it from ClassicFirearms if possible, they seem to provide reasonable consistency and good price. LGS quotes I got at the time were slightly higher. Buying privately, you can apparently get a good deal if you're good at appraising them, but I personally didn't want to deal with the bullshit of sniffing out a million hidden issues like a used car. Didn't seem worth saving what, $20-50?