I am new to the duece. I have owned mine since Sept 2008, and been working on it with a lot of help from No. 2 Diesel.
I thought it would be more of a chore to maintain and use, but I am pleasantly suprised.
It needs PM like all other vehicles, and if you do like me and change all the filters to the Spin on type, you can expect to pay about $90 year to replace filters and then whatever the Oil costs to replace. This is of course if your motor needs no other work done. My truck's Continental motor was re-built in 1986, and seems to have been well cared for. No leaks other than the occasional weaping around a few different seals but nothing that needs attention.
From what I can tell, all my brakes were replaced, along with the wheel cylinders so that is a major labor intensive project that didn't need to be addressed.
I think if the motor is in good shape, along with your belts hoses and clean fresh anti-freeze, you will only need to worry about the occasional bearing regreasing and or seal replacement on the wheels.
I did a much more thorough restoration however, so my expenses initially were quite a bit more expensive. Body work, paint, parts replacements, and just making it look more new cost some, but now, it needs nothing more than simple PM. It is fun to drive, and for the price since there are so many right now, it's kind of like the 1960's Jeeps that were all over as surplus.
Do yourself one favor...
A lot of research so you can find exactly what you want in the truck.
Soft top?
winch?
single vs duals?
heater/defroster?
It then allows you to get something you want and not spend extra money to make a truck into something you want.