I agree. Some of these models are almost impossible to get parts for. For Yamars, Hoyts site has good information on which models not to buy. The 3 numbered Yanmars were not grey models, but still some of these models are models you should avoid since parts are almost non existent. I am sure I will have issues for some parts of mine down the road. Doing the research is imperative before buying one!
Some of the gray market tractors are "refurbished" in VietNam, where quality control is still an unknown factor. Basically they take a pile of parts and make tractor out of them without worrying too much about tolerances, torque, or whether the part is even made for the tractor. There are dealers here that sell these tractors with a zero or low hour reading on the meter and say they're "rebuilt", etc. By and large the people that have bought them have been sorry.
I've located a couple dealers up in Washington State that I think probably work together. Cee Tee Tractors, and Coldwater Tractors. Cee Tee may be a dealer for Coldwater as Coldwater makes a front end loader and a backhoe that they will install on one of the tractors they sell at additional cost. I think they're both on the up and up as they import directly from Japan.
Hoyes Tractor Parts, Fredericks, and a couple other companies support the grey market Yanmars pretty well, but even Hoyes has a list of models they tell you to avoid, generally because of lack of parts for them.
Since I've solidified the requirements I want in a tractor, I've found that a gray market machine probably won't work for me as I've not found any that have a HST, although the XX10 series Yanmars (1510, 1610, etc.) do have Power Shift. I was looking real hard at getting a YM1510, until I looked close at a couple of pictures of the operator's station. The gear shift is right in front of you, making it hard to get on and off the tractor.
I've considered buying one of the F-series Yanmars, even though they aren't as durable as the older machines, plus the 3 digit F models have a lot of complex electronics-even for the 3PH, but no service or operator's manuals in English. Some of them, like the F15 also have some systemic problems with high-dollar failures, though I can't remember what the problem is right now.
Anyway, the wife and I talked over the B2100 Kubota again, but she's real concerned about the high hours (4,300+ --the hour meter is broken) and the serious amount of neglect the tractor has had... Oh well!!