I think you need to go back to Scotty Dive's post #25. An older Yanmar may not be for you. If you are wanting a warranty on parts availibility you may have to go with some newer model tractor. Pretty sure Hoyes sells a rop kit.
$7,500? It looks like these have ascended into cult favorites like a 57 Chev.
These deserve that status, but for me I wouldn't buy anything that I have to baby to preserve its appearance and resale value. Its just a working tool after all.
For a price comparison there was a clean one (or was it a 186D?) on ebay around $6k for many months.
The previous model YM186D will do the same work, its nearly identical. YM187D was an upgrade with slightly longer wheelbase so more comfortable for the operator, and transmission said to be upgraded. I don't see anything about my 186D's transmission that could be improved. It does feel tight to dismount, no other problems.
Maybe the guy is bluffing on the price. Offer him $5,500. Seems to me that would be top dollar unless it looks showroom new.
I'm glad you located the Ebay YM187D. It's the closest comparable to the one you are looking at.
In 2009 I agonized over going clear to Denver (from Northern California) for a like-new YM187D with every option and implement you can think of, even quick-connect loader forks and power steering, @ $7500. The thing would definitely outlive me, it had extremely low hours and looked showroom new. I reluctantly concluded that after another $1500 to ship the tractor and implements it was more than I wanted to pay.
Instead I bought a thrashed YM186D, $2600 without loader, then another $500 for what it needed immediately - a steering box, and the difflock and alternator mounting tinkered with. It's been dead reliable but it still looks like somebody's angry ex-girlfriend worked it over with a stick. Then finally I found a YM186D with power steering and a loader - this or a 187D with these options is what is ideal in this apple orchard with low overhead clearance. This second one isn't gorgeous either (heck I was better looking 40 years ago too) but it operates flawless. I love the power steering. (Photo, both). This second one's seller listed it at $4,500 then dropped to $3500 in 4 days when he hadn't received any calls (because he described it on CL as 'Tractor $1'). I had noticed it, and jumped when the price dropped. After I discovered it had the power steering option (rare) I think his original price was reasonable.
Back then I gave a lot of thought to buying a new or near-new Mahindra but I couldn't justify the cost. With similar features it might be over $12k used, and on up to maybe $20k with every option that would be reasonable to buy along with a new tractor - matched backhoe etc. Nope, I'm not earning my living with the tractor, that's too much to spend on what is essentially a want not a need.
I hope you find what you are looking for!