Dealers that sell their used tractors through eBay, such as Save on Farm Machinery are a great option. eBay is a reputable service that charges the seller fees, not you.
One great tool in searching for the perfect used tractor is the Used Tractor Price Guide. This 328-page book has comprehensive information about virtually all of the farm tractors that were built from 1939 to 2003.
The Used Tractor Price Guide details forty-four different tractor manufacturers and will probably cover just about any tractor you end up looking at. This price guide is an invaluable tool that will allow you to decide if a seller is charging too much for a particular tractor. Look and see where the tractor is located.
Used tractors that look beat up have probably not been cared for properly. Check out the axles for signs of leaking seals. Inspect the engine for any signs of repair or damage. Most used tractors will probably have signs of engine repairs; it's inevitable for any machinery. If the tractor has two pedals, make sure that both pedals actually work.
Tractors with narrow front ends tend to easily roll over on hills, causing injury or even death. All in all, if you are in the market for a tractor, your best option is to go for a used tractor.