They can go anywhere from $200 to well over $1200, depending on condition and country of manufacture.
The Chinese manufactured several variants of the SKS. Depending on specifics, you may looking at anywhere from $200 - $600+. Paratrooper models and the detachable magazine SKS-M and SKS-D fetch much higher prices than a standard Type 56 carbine.
It depends on what you'll be using it for. The Mosin Nagant is generally more accurate and has a much further range than the SKS. However, the SKS is semi-automatic, smaller and lighter.
Between $250 and $350 for a decent one.
SKS Microfinance was created in 1998.
$150 - $1300, depending on specifics. You could get a non-matching Yugo for between $150 - $250, whereas the much rarer North Korean SKS would be closer to the $1100 - $1300 range.
The D and M models accept AK47 magazines whereas the standard sks has an integral magazine.
100-350
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.
All of the fixed ten round mags are cross compatible, but cannot be used in the SKS-M or SKS-D, both of which use a detachable AK magazine.
Very similar, minor differences,
$100 to over $1000, depending on the specifics.
50-500 USD depending on specifics