Depends on how remote the seller is
how remote the buyer is
how fast you want it
weight of the tractor (you're looking at about 3500 lbs. minimum)
any implements coming with the tractor (takes more room)
I just shipped an excavator from Philadelphia to (outside) Washington, D.C. 160 miles one way. Had to come on a flat bed, by itself.
Quoted $4.00 a mile, 2nd quote was $2.75 a mile. Bargaining took it to $2. a mile. Price shown is door-to-door = not one way.
I would be very hesitant to buy from as far away as you are contemplating.
1) You're going to want to see a used tractor.
2) Unless you're dealing with a dealer, you'll want to hand over the money when you take possession of the tractor.
3) It probably means two trips for you to the seller.
When I bought the above mentioned excavator ($27K), I went to check it out, first. I gave the seller $1,000 non-refundable to hold it for 4 days. He ran his own business so I checked out his reviews on-line, before I went to see the excavator (and before giving him the $1K). Then I arranged for transportation and rode with the transporter to get the excavator. After checking that the excavator was as I last saw it, and before loading, I gave the seller a cashier's check for $26K. I had emailed him an image of the cashier's check the day before. He called my bank to verify that cashier's check was good, and issued to him.
We both were careful. That's what good business is about.
You're not too far from Boston. Co-incidentally, that's not too far from where I bought my 32hp Kubota with loader and backhoe. That time, I'd sent the seller's lawyer $500 to cause the seller to hold the tractor until I got there - purchase subject to inspection. We drove from Wash. DC to western Massachusetts. On approval of the tractor (it only had 39 hours on it), I gave the seller $18,500 in cash and we loaded it up and left for northern Maine.