Having an old dump truck is endlessly useful around the farm. I have an old '75 C-60 chevy with a 14' dump bed that I use all the time. If you have a loader that can reach over the sideboards go ahead and get a 2-ton or larger truck vs a 1-ton. You'll get so much more work done in the same amount of time it's not even comparable. Also, if you are going to be using it primarily off-road and around the farm I'd suggest one with some of the smaller gas engine offerings, you want it as light as possible on the front end otherwise you'll be stuck a lot.
As for costs involved, it just depends on what you get. The parts for my old Chevy are pretty cheap and plentiful, I just rebuilt the rear wheel brake cylinders on one side last week for a grand total of $23. Brake shoes all around are about $200, tires aren't cheap but they last forever with this type of use. And it's got a 350 so motor parts are available anywhere. I have farm use tags on it so insurance is very cheap, and no licensing or registration. Even with 'Farm Vehicle' tags which is what my father runs on his International dump I think they are only $100-120 a year for 33K tags. If you can't register it through a farm its more than double that however.
