I just completed this last Saturday. I have the sport package with 20" wheels and flares. The entire process took me about 4 hours - 3 for the first side, and 1 for the second
. I shopped around locally and found the kit for $330.
A few tips i picked up:
The instructions show to remove 2 rivets in the rear fender flares, but you should remove 3 to give yourself enough room to get the running board connector out/back in.
You also need to remove 2 rivets in the front - there is a small lip that fits inside the top of the running board.
The large connectors in the bottom can be easily removed with a pair of needlenose pliers - just pull straight down, and new ones are included in the kit.
When you remove the old trim, quite a few of the panel connectors will break and remain in the car. A panel trim remover comes in handy here. I picked one up at the auto parts store for $7.
After you have removed the trim, make sure all of the rubber O-rings are removed from the car. Or the new trim will not fit correctly.
The new running boards actuall come with no assembly instructions. it takes a few minutes, but they are not that hard to figure out. Dont throw away the black styrofoam pieces.
The only other issue is replacing the rivets. If you are not removing the tires (as I did), you have to use a 90 degree rivet gun. The other option is to buy rivets from BMW (or Advance Auto, etc) that are the plastice screw in type.
Hope this helps.