I need to find new or used window regulators for all the doors because the front driver side the front passengers side and the rear drivers side window regulators are badly damaged. Well the rear drivers side window completly broke so I have to push up the window with my hand. (You can see the car on my profile.)
These are a common enough failure that the BMW dealer is probably the best place to purchase the parts. They sell the motor and the regulator parts separately. The parts are not all that expensive. Check out Bavauto.com as well, they should have your parts in stock and might even have installation instructions online.
check out e46fanatics.com for detailed step by step instructions for the window regulators. New ones from the dealer cost about 60-90 dollars depending on front/rear and sedan/coupe each. Good luck.