I paid $159 straight out of it’s original packaging. It still has a lot of storage “gunk.” The dealer had gotten it when he bought a “liquidation lot” from an estate sale. He looked it over but had no interest in this type of firearm.
I just decosmolined a Yugo SKS. Using mineral spirits soak the small parts in a trough & the receiver/barrel in a length of PVC pipe. Scrub with a bristle brush; a fridge condenser brush works for the stock inletted areas. Rinse with hot water & set aside to dry, took a few days for mine.
What emerged was a like brand new SKS.
If you paid $159 for a genuine Mosin Nagant sniper rifle, you got a cinderella deal! They are often faked up- real ones are going for >$600.
Try www.7.62x54r.net for info. There are also a number of Mosin Nagant groups of Facebook (I’m in two of them) that can help you find out all kinds of info.
There are as many ways of removing cosmoline as there are shooters- I favor low odor mineral spirits and an cut up t-shirt. Be sure to clean the chamber thouroughly- old cosmoline and the laquer on the shells can mix with the heat of firing it, which is the cause of the “sticky bolt” syndrome you’ll be hearing about.