I buy and sell allot of John Deere Equipment.  There are allot of people out there scamming on John Deere tractors and lawn equipment.  One  easy thing  you can do is offer to come get the Item in person, if they don't want you to do that its a scam.   I love it when people come get things in person because it eliminates a bunch of work for me and they get to see what they are getting before they pay for it.
   There are also no titles or other government documents that go with equipment, so that another red flag if they offer to clear titles or cover transfer fees, there is no such thing!!  
    Ask for a reference from other customers, or dealers. Ask for there address and other phone numbers.   These all work to make sure your really buying something.   Finally  Its next to impossible to buy somthing for Let's say half price of market value,  There are too many guys just like myself that will  buy it at wholesale just to have it in inventory. I hope this helps.    www.greenpowermowers.com