What do these sell for? I was told that the factory magazine are superior to aftermarket mags?

Anywhere between $90-$110 depending on condition. Last time I looked, that's what they were anyway, 8 months ago.

Yes -mostly true

Holy Crap!!!  I used to pay around 35$ for those!

From what I remember...there was one manufacturer other than Ruger that made good quality ones...the rest were junk.  Does anyone remember?  

How do I tell if they are factory? What will the floorplate say?

Rich:

They have ruger floor plates. The newer ones are stamped on the side of the mag body. The new (post ban) ones I saw but could not buy (20 rd) also were marked MIL/LEO. I know there is little love for the mini here but honestly mine has 700-800 rounds thru it without issue so far. The magazine issue the biggest negative IMHO.
If you want all the MINI info you can handle go to www.perfectunion.com. It is the mini14 version of arfcom. There are tons of aftermarket mags for the mini but only a couple brands aside from ruger mags that function reasonably well in the gun. I got mine during the ban and my options were (and still are) 5 rd ruger mags and 10 round aftermarkets I bought 20 - 10 rounders and chucked 7-8 that did not function after trying to tweak them

The mag plate on the two I saw say McCoy Mobil any idea what that is?

The PMI mags (Formerly the Old federal Ordanance) are Identical to the Ruger Factory mags (Except for the Ruger Markings) and are much more reasonably priced. I heard PMI actually mfg. the mags for ruger. So if you can find some buy them.

With all the other aftermarket Mini 14 mags reliability is a crapshoot!

Never heard of Mccoy Mobil but PMI were one of the brands of "good" mags as the previous poster mentioned - now that I've thought a bit i *think* the other decent  mags that fed well were John Masen or Mason brand???

Thanks for the info. I'm trying to find more info on these mobil mags because I'm trying to get a price point for selling them.