The accuracy on some SKS can be made really good if you are willing to do the work on them. sum moa to 1.5moa type of range. In their stock form, with a lack of bedding and standard sights you are looking more at 4-5MOA. Not too bad. The M16 only requires 4MOA to pass spec.
Bed the action properly to take out the slack in the stock, stick on a tech-sight ts200 peep sight and clean up the trigger group and the accuracy of the SKS really starts going up. Thats going to start adding money to the cost.
There are also plenty of other modifications. Rails and scope mounts, other rear or front sights, replacement trigger action springs, modified firing pins with a return spring, a buffer for the recoil spring, plenty of different gas tubes to avoid it touching the rest of the rifle, plenty of different stocks.
The SKS makes a fun project gun, or a truck gun, or when you want something as reliable as they come to pull out when its needed.