If that tractor is showroom clean, the price is about $2000 high. The tractor has no warranty and it has been used for 220 hours (-$3000 because of no warranty and -$3300 for the hours). Would you rent me a brand new tractor for $15 per hour? That's what $3300 is. I think I know the answer.
I would offer $19,500 if it is being sold by an individual and $20,000 tops if being sold by a dealer. I might go up a little if it is being offered by a dealer and they will throw in a full service with hydraulic oil and filter change included. I'm thinking the tractor is worth about $6000 less than new. As long as it is maintained properly, it will hold its value pretty well for about two more years and then drop at a rate of about $1000 per year until it reaches about $10k to $12k where it will bottom out and maintain it's value for many years after that.