As far as factory holes, for the power mirror option, yes, for manual, no. But just a few holes and that's it. I got the bolts, gaskets, I still have to get the mounting plate. It goes inside the door to the inside of the outer skin.
How much they cost? hmmm, if you can find them grab them! It's a discontinued part.
I have not seen any through regular channels like lmc or the likes.
I think I am going back out saturday to get the mounting plate and try not to make a mess.
You can find these mirrors on 90-91 burbs, crewcabs and full size blazers. Keep your eyes out to see what they look like installed, pretty sharp.