From a gun dealer. Legally the bare receiver IS a firearm, and you will need to go through the same processes as if you were buying an entire gun.
SKS receivers are milled. AK receivers can be stamped or milled.
Try the receiver
A brand new SKS stripped receiver, depending upon manufacturer, will sell in the range $US 45 to $65. A receiver, with all fire control parts except stock and barrel, should sell for approx. $120 - $130.
The best place to buy SKS mags would be Tapco. Drums maybe.
Check the receiver.
The RUSSIAN SKS may be date marked on top of the receiver cover (properly called the rear housing) , along with the symbol of the arsenal that made it.
You do not say who made your SKS.That helps and usually the russian made SKS rifles will have the year of production stamped on the receiver cover.I am not so sure on the Norinco made ones.
On the receiver. left side, just below the bolt.
Year of Manufacture is stamped behind the serial # on the left side of the receiver.
SKS Microfinance was created in 1998.
The D and M models accept AK47 magazines whereas the standard sks has an integral magazine.
The only SKS carbines currently which require registration are the Chinese-made SKS-M and SKS-D models. Those could not be imported into the state after 1989, and had to be registered by 2000.