There are reasons, other than simple gouging, on why parts run so high within any dealer distribution network. Last article that I remember seeing addressed cars, maybe 10 or 15 years ago, but I'm sure there is still truth to it. At that time, they stated that the cost of building a car from parts (retail price) ran somewhere around 10 times the retail cost of the car itself. Factors: Dealers are expected to have on hand just about every part, for every model, going back 20 years or more. Parts are overly produced, just to meet the stocking demands. Those parts may occupy shelving space for 10 years before they are sold, if ever sold at all. As consumers, we don't want to hear 'It has be shipped from so-and-so, should be here in a week.' We want the parts, and we want them now. And we want somebody standing ready at the parts counter when we walk in, or to answer the phone (employees do cost money, lots of money above and beyond wages).
I except that the parts overhead for JD, Kubota, NH is around the same as for Ford, GM, Honda, etc. Now, you can reduce the overhead equation by buying a Gray-Market tractor. Parts warehoused in one centralized place, probably in China. Just don't get too upset when they tell you it will arrive in six months.
Roy