They must have made a crap load of those old Ford tractors. At least in Ohio here, you can not take a Sunday country drive, without seeing at least 2 of them in some kind of flavor.Our local antique tractor club put together a special show just for the Fords, because they are so abundant they were taking space away from other rarer tractors being showed. You see them vintage 1940'sto1970's Jubille Type Ford's for sale. Fully functional but beat up a bit for like 1500 bucks all day. The farmer next door one he uses for a tool around, and still gets every part he needs from the local NAPA dealer.
When Ford re-entered the tractor market in '39 he had some things none of the other tractor makers had- a dealer network (larger than any other tractor company by far) already widely established across the nation, a well known name and reputation that was already established and above all else- FINANCING! Harry Fergusons 3pt hitch wasn't the reason they sold, that hitch was just as proprietary when it was introduced as any other companies effort at designing a "better" hitch system. The "N" series sold because they were cheap tractors that had easy financing and Ford made implements to fit the tractor. They were the H+R or Stevens or Iver Johnson in that market. When the antique tractor craze started in the mid 80's any old N series $250.00 tractor was suddenly worth 1500.00. There was a period where a decent example would bring $4-6k. Rougher examples that could be picked up for $12-1500 had thousands in parts, tires and paint thrown at them so they could get a prize at a tractor show. Today those tractors might bring $2500 if they are really nice, but more likely $1500.00 is realistic.
I'm not a fan of the N series Fords. You get into the later hundred or better the Thousand series and then you have a decent tractor. It's like the people that go ga-ga over VW Bugs or early Mustangs or early Corvettes- the product itself isn't worth what the perceived value is. The Bugs were junk, the 'Stangs were economy cars and the 'Vettes were terrible handling cars for what they were trying to be. Get into the later years, at least with Ford and Chev and you get a much better product.
Thus endeth the sermon...
ETA- No offense to any lovers of Bugs, early Mustangs or Corvettes. They were just the examples that came to mind. To each their own and enjoy!