ditto everyone else comments more so posting in Buying/Pricing/Comparisons forum.
i placed a ""space"" just after www. on below links, so you can actually see website names.
then right below i removed the space to make it easier for you click and go.
www. tractorhouse.com
www.tractorhouse.com
www. craigslist.org
((use www. searchtempest.com to make searching craigslist easier, allows you to search multi cities in your area at one time))
craigslist: chicago classifieds for jobs, apartments, personals, for sale, services, community, and events
SearchTempest - The EASY way to search Craigslist
www. ironsearch.com
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above 3 websites err 4 websites i should say. should allow you to narrow down pretty good on used tractors. do not be in a rush to buy something if you are looking for a deal. if you can wait a couple months or little longer you can normally find a better deal here or there.
buying used means knowing how to check a tractor and make sure it is not going to be a dead tractor. example letting it run in high idle for say 30 minutes, and then check for leaks. and trying all hyd and see if they are loose or not. example raising all hyd up shutting off tractor and letting it set there for 30 minutes and see if things fall back down.
tred on tires can be very important. new tires for tractors can be very expensive. tractor tires are not car tires. and in that cost a good amount of cash. if just half the tred is missing it can mean a lot less over all traction compared to a full tred new tractor tires.
use equipment = extra maintenance and repairs. if you are not mechanically inclined. use stuff can be very very bad. and can be just as expensive as a new tractor if you are paying someone else to do repairs. if you are doing repairs yourself. john deer and ford/newholland have descent "tractor parts" with diagrams on there websites for majority of things. some other manufacturers are not as good. or you have to pay to see.
AGCO Parts Books also has some part books for good amount of other manufacturers as well.
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again hit the buy/pricing/comparision forum on TBN, give details of how many acres you want to mow, and anything else you might want to do with the tractor. and folks can help ya narrow down a size of tractor that should work better for you for majority of things you want to do if not all the things. that way when looking at the given links i noted above, you have a better idea of what to look for. without as much worry of getting something to small or to large for what meets your needs.