Yes, SKS's are cheap, my friend bought his for 170 [+/-] w/ a folding stock, scope, bayonett, and grenade launcher mount already attached. The only problem he has with it is that every time he racks the bolt, it fires the chambered round. I'm not sure if he got that fixed yet.
I bought my AK47 new for 330. Yes, it was a little more, but I know what the gun has been through, and I think it is a better base weapon for high end accessories.
But, the big question is, how much you want to pay.
Back to my friend's SKS - he has detachable magazines, although I am not exactly sure how you would go about converting it. I've also heard that you can make the SKS accept regular AK mags. I haven't personally witnessed this though.