You've recieved excellent advice.
You will only find a project machine for $6,000. Parts alone can easily cost more than that when it breaks down, and IT WILL break down. All tractors wear out, but track machines are gonna be more expensive and more dificult to fix. One that cheap is gonna be very wore out and will need allot of care.
Never trust the hour meter. 3,000 hours isnt' much on a machine, so if you find one with that many hours, it's wrong. That's not even two years worth of regular work. It's not uncommon for a ten year old machine to have 15,000 hours on it!!!!
Finding an undercairage with minimal wear is pretty hard to do. Allot of machines are sold be cause nobody wants to pay for a new undercairage. If the pins haven't been turned, than you can have that done for under a grand, but if they ahve been turned and both sides are worn, than you'll need new tracks. Tracks on small dozers can run from $3,000 on up depending on how common they are. Sprockets are cheap. A couple of hundred per side is about average. The idlers can be bought one at a time as needed, so that's not too bad.
For this reason, the seller will always be on the generous side on the amount of wear on the undercaraige. They will advertise it as a certain amount and it's up to you to figure out how accurate that is. 50% is pretty bad, so if he's advertising it at that amount, it could easily be 30%, wich would be terrible.
A worn undercairge will mean tracks slipping off. Losing a track is always a nightmare, but losing it out in the field, in the woods or in any other location other than in front of your shop could be one of the worse experiences of your life. If you can't replace it yourself, it could also be very, very expensive. You ever see a tracked machine sitting in a field or some woods someplace? It because the owner can't afford to have it fixed. Sometimes it's just not worth it.
When my hydraulic pump started acting up, I had the dozer shiped to Case to look at it. Cost was $400 round trip just to get it there and back. For another $500 they told me that all three pumps were bad and that it would cost $18,000 each to replace them. Yes, $54,000 for the repair if they were to do it for me. I later found out it was just out of adjustment after the problem started to fix itself. I did rebuild one pump and drive motor for $3,000 and my labor, but that was a differnt problem.
Can you do the repairs yourself? If not, don't expect anybody else to. You are way down at the bottom of EVERYBODIES priority list if you need help. Tractor mechanics can just about write there own ticket on what jobs they decide to take, and comeing out to your farm to work on your older machine wont' interest anybody who got worked lined up on $100,000 to $500,000 machines.
One very common repair that you will have to do will be to rebuild the hydraulic cylinders. You can gurantee that a few, if not all of them are worn. If they are not leaking today, they will in a few months. One at a time, or several will start to leak on you. If you ignore it, it will just get worse. Hose will also break all the time, but those are real easy to change.
Before you decide to buy a machine, it might help to know why you want it and what need to do with it. Track machines are not very good toys to buy in order to just have around. The maintenance on them is terrible, they beat you up driving them and they suck up allot more fuel than an equal HP wheeled tractor will.
Can you weld? Can you take of one inch bolts? What about larger ones? I have a 3/4 impact wrench that I use on mine. My half inch 500 pound wrench is way too small.
How old is the machine? I know you haven't found one yet, but finding parts for older machines can be very time consuming and expensive. What will you do if your hydraulic pump fails? What about the clutches? The list is almost endless and I'm not just saying this to scare you. I'm saying this because I've been there and I'm still there.
Right now my dozer is down because my pivot pin on my blade is wore out. Parts are almost $3,000 for new stuff. I've come up with a way to weld some 1 1/2 inch plate to one piece of it and 1 inch plate to the other sides to create a point that will rub and wear out over time, but not very quickly. I've had to have somebody else do most of the work because I'm not good enough to make sure it will hold together, nor do I have to tools to cut that thick of material precicely. I'm hoping to get it done for under $500, but so far, it's been almost a month and I'm running into nothing but delays. It's always one issue after another.
If it's just a few jobs, it's far cheaper to hire it out. It doesn't matter what the operator you hire charges, it's gonna be cheaper. If you know how to run the equipment, or don't mind paying to learn, than you can rent most heavy equipment. The problem with renting is you might spend three days doing half a days worth of work. Not that I'm trying to be rude, it's just what I've observed with my own dad who liked to run my dozer. Some things he can do, others he can't. He doesn't know the difference, so I have to be very careful in what I let him do and what I keep him away from.
The day I sell my dozer will be a day of celebration!!!!
Eddie