In good condition, the current market is $200-$300. SKS were cheaper than dirt in the early 90s. You could get them in unissued condition for $75. Like anything else military and semiautomatic, they have increased in price over the years. They are not much for looks or target accuracy, but they are usually dead reliable. A matching numbers gun with a blade bayonet might bring a premium, but generally any variation or manufacturer is not going to bring more than $400 at the most.