Ah...I know the type well. Quite honestly, I have been successful in purchasing items from such men, but it takes TIME and PATIENCE. Best thing I have been able to do thus far, to really move a stubborn fella, nudge him to stop by MY PLACE, or to visit a local show where I am exhibiting. Seeing the care and appreciation I put into my collection has won over several stubborn collectors. After being told NO, I will also offer my assistance in finding parts, manuals or fixing any tractor issues he may have. Everyone 'collects' in their own way, so sometimes it just takes a little sharing/caring to bring home the iron. I'm not just out to grab as much as I can...I'm looking for a fair buy on something I'd like to have, and I will look to make a new friend in the hobby. Local allies can go a long way.
Something else I like to do, and for no other reason than to be personable and friendly, send them an email or call them about a year later. I mark the anniversary of such 'wins' on my computer calendar. I fill them in on how their old equipment is holding up, or what I have done to improve it. Recently, I sent out an invite to an older gentleman who met me at a local show, before agreeing to sell my his old Landlord...to come visit me at that same show this year, to see his old tractor on display, decked out with factory accessories and attachments.
After all this, next thing you know, that stubborn guy may or may not sell to you, but it's likely he begins telling you of his 'friends' who also have machines of interest!