If want it to just drive around, get ready to spend some bucks. Diesel cost more then premium unleaded, oil changes are 100.00 if you do them yourself but every 5k miles isnt bad. Power strokes need new fuel filters every 15k, do your homework and make you get one with a clean oasis report, you dont want a lemon with a diesel. Now I love my Powerstroke. If you buy Ford, stay away from the 6.0's that are 06 an older unless you can confirm head stud replacement, 08 and up I have not heard of any issues. Do some research at Ford Powerstroke Forum. They are just like us but with Ford Trucks. Good luck bro.
Diesel fuel prices are stupid and suck. Right now I can get it for $3.79 but reg is $3.59 so like he said get ready for big gas bills. I am getting 19mpg out of my 09 Silverado 2500 with the allison trans. I love the truck and wouldn't trade it but I am getting sick of $500+ each month to drive it. As for the $100 oil change Go to walmart. I only spend about $40 to get mine done and they use 10 qt of rotella. The store I goto bases it off the regular oil change price and charge for the extra oil and that's it.