I looked for a used ATV from October till early december and found a lot of over priced junk out there. Kijiji is the best place to look for a used bike but you need to be on top of it as the good deals go fast. I ended up at a dealer allterraindomain.ca Rob was a real good salesman and I hate salesmen. He sells new and used atvs and is a great source of info to help put you in the right atv for your needs. For the used market this year in my price range I did pretty well, I got a 06 Polaris Sportsman 500HO red flare package with new 27" lpt mud lite tires, warn winch and plow mount, 400 miles and under 100 hours for $4200 mint condition.
What I learned from my search
Stay away from the no name brands like baja
Polaris are heavy witch is good for pushing snow, not desighned as well as the big names if your hard core, nice looking bikes,costs a little less.
yamaha brute force is a sweet bike
Honda has very good bikes but at the top of the price range
atv.com is the best site for research
Always check if the odometer is in miles or kms
Steve