FITS explained it pretty much the way it is ...
I purchased a new (authentic) factory folder Mini-14 Ranch Rifle about a year-and-a-half-ago. The model code is 'KMINI 14 5RF". 'K' designates it as being stainless steel. '5' indicates the factory shipped it with a five round magazine (the highest capacity rifle magazine generally permited in Canada with only a few exceptions). 'R' meaning 'Ranch' and 'F' being folding stock. Sturm Ruger was unable to confirm that it was "the last" factory folder sold to a civilian, but in a letter dated July 2001 they did say that factory folders were being phased out of production. The western Canadian distributor for Sturm Ruger, (Inland Pacific Co.), told the gun dealer where I purchased the Mini that it would be the last Mini 14 factory folder to come into Canada.
When it began to sink in that the FF stock would soon be collectable, I decided to put the stock away for safe keeping and order another FF stock from Sturm Ruger so I could take the gun into the bush and not have to worry about getting it scratched and dinged up. It turns out that Sturm Ruger was not even able to get me another folding stock, so I bought a Butler Creek folder that I like very much. The Butler Creek is a rugged, good looking stock but makes the rifle considerably heavier (compared to the FF wooden stock).
As previously mentioned, the rear sight is a bit 'whimpy' but it permits easy installation of a scope and mounts. (The receiver is machined with 'half moon' slots for quick attachment of scope rings. This was the whole concept behind the Ranch model). I like the looks of a 'non-ranch' Mini 14 better but mounting a scope is more of a bother (and you need a deflector for the brass).
As for price, well, you can factor in about 1/3 of the cost is for the 'novelty' of owning a Mini 14 (Thank You "A" Team). It is not, IMHO, a poor rifle at all, but the extra money you pay is not for it's quality. An AR15 is a better rifle all around (accuracy, ruggedness and ease of assy/disassy).
Reference as to identifying non-FF stocks, I can't help you out much there except to say that my FF stock hasn't any markings or insignia of any type that I can find. Also, I am reasonably certain that you can't duplicate a FF stock buy simply cutting down a full factory wooden stock. The contours in the grip area of the two stocks are noticably quite different.
To learn more about Mini 14's, check out a handbook published by Paladin Press entitled "The Mini-14". It was written by Duncan Long and gives a good history of the model with lots of technical data. The book was copyrighted 1987 (pre-ban) so of course the info is dated. It is still a good resourse book if you like Mini's.
As for a price, well what can you say? I know I paid too much for mine because I wanted it very badly. Like anything else, you might get a good deal if the seller needs the cash or doesn't know what the market will bear. I know a guy who got a screaming deal on his because (I strongly suspect) that the seller thought that this particular model was about to become prohibited. The seller didn't check out the new laws carefully and dumped the rifle for considerably less than what he could have gotten. Don't wait too long for deal, though, I haven't seen too many true FF stocks around.
Anyway, good luck on your search. I hope you find what you're looking for ...