I guess it depends on how much they are selling it for. My dad bought his 2000 PSD, 4WD, Dually, Crew Cab, Long Bed 50K in 2003 for around $23K. I personally would want to buy a truck that had less miles, just because I would plan on driving it a LONG time.
Honestly, 230K probably still has some great life left in it. My dad sold his 95 Powerstroke with 300K miles in 2003. The engine was still running fantastic, but the rest of the truck was falling apart. If the whole truck looks like it has been taken cared of, and depending on the price, it might be a good deal!
Hope that helped