Odds are the sun roof may have come off its track. Its easy to see if it has, but rquires removal of the motor to reset.
Check ALL of your fuses. One may be bad and be tied into something thats not listed. Better to check em all and make sure. If the windows dont roll down all the way it could be a few things, but the best way to check is to remove the door panel. That way you can see if its off the track or anything is broken. It is kinda common to have a few issues with the windows. A window regulator can be had for a LOT cheaper then $800. Places like Pelican Parts, GetBMWParts.com, and Bimmerspecialist.com should sell them.