
MB421471 is the part number for the front door window run channel (the flocked rubber bit that the glass slides in). US$27 each from Amayama.com.
Also consider replacing the lower trim strips- the outer ones (MB421515 and MB421516) get hard with age and let water into the door, the inner ones (MB421535, MB421536) get torn and let cold air blow up the inside of the window.