I have had good luck buying used myself, but sometimes it has been helpful to compare what you can get new as well. If you are borrowing for the truck the interest rate will likely be less on a new vs. used vehicle. With new you also get a warranty (Ram is 5 year, 100k), new tires, new brakes, new battery, etc. What is that worth? Just for comparison here is a new Ram Crew Cab in cherry red or white for $33k in Eugene. From everything I have read the 6.4L looks to be a good engine with pretty reasonable milage (ask ib516).
Ram 2500 Tradesman Crew cab w/6.4LThe Ducks are playing at the Rose Bowl so traffic won't be too bad if you wanted to take a look. :)
As mentioned I have had luck with used myself, but have also chosen to buy new when the benefit outweighed the cost. Especially when I planned on keeping the vehicle a long time.
Good luck,
Stu