A good way is to just watch the classifieds here, tractorhouse, and various Craig's lists, to get an idea what they sell for. Then, when you see a good tractor at a fair price, you can move. Remember, dealer's prices will be higher than private sales (expect to see the same machines for sale for a long while, if they are pricey), and sales tax may be an issue- here in Maryland, tax would be 1,200 bucks on a $20,000 machine. Some dealers, like Messick's in PA, seem to price their used equipment pretty fairly, so I wouldn't expect much discount from what they are asking. I got a "free" Kubota steering knob, but all told, my price was fair for what I bought. No complaints. My next tractor was a private sale, also what I considered a fair price. Considering what I got, I am very happy with the particular tractor and it's "options".