I'm not a fan of folding stocks so my Mini has the original, polymer stock on it.
Magazine quality will vary from very good to very bad depending upon the manufacturer. For high-capacity purposes, I like the 20-round Ruger factory magazines. Ruger won't officially sell them to "civilians" and even goes so far as to stamp "For Law Enforcement/Government Use Only" on them, but many gun shops sell them for $35 to $45 based upon prices I have seen. They cost a little more but the quality is top notch.
For those that like to claim that Mini-14's aren't accurate, I just shot a five-shot, 2.25" 100-yard group two days ago, with four of the five shots going into 1.75". This with a stock, pre-580 series ranch rifle and a Leupold 4X scope.
As to the Mini-30, I have never owned one but my understanding is that they tend to be less accurate as the Mini-14, and reviews I have read of them seem to bear this out. In one side-by-side test the SKS gave a much better performance than the Mini-30. If you decide to go 7.62x39 instead of 5.56x45, there are some nice AK-pattern rifles for sale right at or a little less than the cost of a Mini-14. AK magazines are cheap and plentiful, too.
