I just replaced the first injector ($320) on my 03 Cummins at 611,000 kms. The other five are still original. Only other engine related items in that time were a lift pump ($220), alternator ($125), water pump twice ($75 x 2). All the other wear items (brakes, front end, tires) are no more expensive than they are for a gasser.
It was said earlier in this thread and it's been said before.....buy what YOU want and drive what YOU want, life is to short.
1990 Jayco 250 Special
2008 Ram 5500 DRW 6.7, Cummins, Aisin auto
Holland/Binkley 5th wheel, Reese Dual Cam, and more
232,500 kms in 2013
200,000 kms in 2014
160,000 kms in 2015