A friend and I recently ordered a couple of NIB stainless ranch rifles with synthetic stocks. Dealer cost was (I think) about $445 plus shipping. We paid the dealer an additional $30 for handling the deal for us. This beat Walmart and local stores, which sell them for around $500-$550 here. Of course, a standard (non-ranch) Mini-14 sells for $20-$30 less, and I think we paid a little extra for the synthetic stock (although I'm not sure of this). I would say that a used stainless Ranch rifle, in excellent shape, with the Ruger scope rings, would be worth around $400-$450. but that's just my estimate.
I pretty much agree with the previous post about the magazines - if they are Ruger or PMI, they are worth quite a lot. But they probably are another brand, and if so, may not be worth much at all. If you can verify that they work well, then I would say they are worth $10-$20 each. If they don't work well, they aren't worth much (if anything at all). I do have some U.S.A. brand Mini-14 20-round magazines in stainless (or maybe nickel) that work perfectly in my Ranch rifle, so don't automatically assume that all non-Ruger or non-PMI magazines are useless. I haven't had any problems with these USAs and wish I'd bought more of them. They had such a bad reputation that I thought I was probably just throwing money away when I got them.
Doug