I think this has the potential of severely hurting YOUR reputation. If he does a lot of talking, and tells people that you balked at paying a bill (of course he will leave out the 5 years to complete the project part), people will start having second thoughts about doing business with you. Right or wrong, I see that as a possibility. I think I would get it taken care of just as soon as possible, enjoy having the convenience of an extra reliable auger and chore tractor around, and move on. I have spent more on more foolish stuff. That tractor should have itself paid for again in another 40 years, and I wouldn't be at all surprised if it is still going strong then.

Most times education like this takes some high priced college-and about 5 years of it.