You are drastically underestimating the cost of a quality restoration. If you use all OEM parts when you rebuild the engine you may have $6-700 in that alone. I fell into this trap, too...it costs a LOT more than you'd think to restore one of these and do a good job. Somewhere I've got an excel spreadsheet for everything I spent on this 100 when I restored it 3 years ago:
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The engine got a new rod, (aftermarket) piston, and rings (no machine work was done), clutch, paint, gaskets and seals in rearend and engine, I made a new wiring harness, rebuilt the steering box, and basically fixed everything that was wrong with it to make it into a new tractor again. I tried to save some money by using an aftermarket piston, making some of the rearend gaskets and wiring harness. I put on 4 nice, used tires that cost me almost nothing. I had a 3-point, spring assist, and lights laying around that I added to increase the value. I spent weeks researching to find the best deals on all of the parts I needed so I would spend the least amount of money possible. I sold it as you see in the picture and got $1250 for it. That is essentially what I had in it, and it took me 6 months to find someone that would pay that. If it didn't have those options and the plow, I probably never would have gotten that much for it.
If you have to do any machine work to the engine or replace any really expensive, harder-to-find parts, and buy new tires, you'll easily have $2000 or so in it, and it's probably worth half that with no attachments and few options.