I am a little late, I just ran across this thread. I recently bought a Romanian SKS from AIMSurplus. It was in very used condition. It was $139.95.
After looking it over in their store, I took it home. Since I have been hanging around TFL for a while now, I knew some of the things to look for.
I went to the ak-47 page and copied their disassembly instructions. Very easy to do!
I found that the firing pin and bolt were very dirty, so I took them apart and cleaned them real well. Only one pin to remove and it's apart. What surprised me was when I took the gas tube off the gun. The piston was frozen inside the tube and the gas port was plugged solid!! With some gentle tapping on the small end, I got it to come out. Inspecting the piston showed some erosion around the end. I cleaned out the tube with a brass brush for my .50 cal. muzzleloader. After a thorough cleaning of the entire gun, I was a little unsure of how it would work.
I got to take it out a few days later and was pleasantly surprised to find that it worked flawlessly! My GF and I put about 120 rounds of German surplus rounds thru it and found it very fun to shoot!
As others have posted here before, make sure the firing pin and bolt assembly are kept clean. I will also recommend cleaning the gas tube and piston regularly.
I am anxious to take it out again!
Dennie NRA Life Member, GOA