http://www.jgsales.com/c-r-guns-c-290.html
That's a good place to start. I bought a Ishy round receiver off of them when they were around $79 or so. I didn't really know what I was getting got a 1942 all matching, of course, covered in cosmoline.
I've never disassembled the rifle again after initially doing it to get the cosmoline OUT, and I don't believe you need to. After shooting it a few times and cleaning the heck out of the bore, it looks better down there than it did. It shoots to POA so I'm not too worried about it. Ammonia is the way to go if you really want to make sure you get the salts out, but I've never been done wrong with Hopps followed by a couple patches of CLP.
The point is, I don't really think you need to pay that kind of coin if you're looking for a standard issue Mosin (which it seems like you are). If you're not a collector of Mosins, I hardly see the point in plunking down extra coin for what is essentially just a milsurp gun. Ammo is still cheap and plentiful and showing no signs of waning demand so spending more money seems counterproductive. The accessories are nice but not a deal maker. If you are fortunate enough to have a C&R then jgsales.com is the way to go. I didn't, but still only paid about $17 in freight and the $25 transfer. I still made out like a bandit.