I have never had to rebuild one. There are to many good used engines out there to buy o9n the cheap to have to rebuild one for now. I just bought a 25k mile 7.3l idi from pick and pull for $254. I know the mileage because my full time mechanic actually put it in the truck we pulled it from. Dumb luck yes, but I have never paid more then $400 for a good used IDI. The power strokes command much more money then that for a good used engine. If you sell a good used powerstroke for less then $700 you are leaving to much on the table.
As you posted in in your other post to, injectors are $500 to $1000 rebuilt. I can get a new set of injectors for an idi for $80, I even paid as little as $64 for 8, for 5 sets from uhaul. IDI is WAY cheaper all the way around to replace parts, or replace with a used engine. If you want power and noise on the other hand, the powerstroke IS the way to go. Just doesn't fit into my fleet though unless I want to spend a lot more money to maintain the amount of trucks I have on the road at one time.