One major issue with 03-05 duramax's were the injectors. There was a recall on them. My dads 04 went through 4 sets in the first 150K, all were covered. The last set they finally fixed the problem with the injector itself and took the truck from 150 to 260K miles when he sold the truck. Its still running around today.
Other than that truck was pretty bullet proof.
O' and that is way to much for an 05'. Sure some one may come up with the cash. But I would not. In my opinion I'd be willing to pay 20-24K. For a low mileage rust free WI truck.