12k is a lot for a machine of the 5575s vintage even with low hours, in todays market imo..
Believe the 240 to be a solid machine and should be near your budget with average hours (2000-3000)
As with any used machine test all the functions and see how it starts cold.Look for loose pins, oil leakes, cylinders that leak down (boom drops or bucket tilts on its own)
Ken
I owned a John Deere 250 for about 6 months before moving it down the line. My machine had a little under 3000 hours and I picked it up for $9500.
The first thing to look for is under the cab. Raise the arms up and remove the two cab bolts. ROll the cab up. First off you will notice that JD SS's have more wiring than I can see a need for. Make sure its all good. Next check for leaks. Mine had two leaks when I bought it and seemed to have a new leak about every 100 hours.
If that all checks out put the cab down and start it up. Run it hard for about 1/2 hour. Move Gravel Move pallets but work it. Once its warmed up remove the oil cap and look for blowby. That is not neccessarily a JD thing as mine had a great engine.
That being said the 250 was a good machine. The stability and lift are underated in my opinion. My 250 with countweights was just a shade below my current 873 in lift I feel.
Where you need to be careful with the JD is electrical. In 6 months I sunk over $3000 into electrical problems and have read many of the same things right here in the JD skidsteer forums.
Sorry but on the older series I know very little.
good luck,
Dozer