5-series wagon/touring is kinda rare it's no 508, Z8, Alpina turbo, etc. KBB's prices should reflect market prices, unlike my 1988 Mazda 323GTX...
aside from the replacement tranny most those "repairs" are just maintenence for a BMW of that vintage. but the tranny probably cost $3k to replace.
when does a serpentine/fan belt last past 100k? those early water pumps liked to fail and pitch the fan into the radiator, likely changed to the newer part. the plastic/aluminum radiator starts leaking at the seams. swaybar endlinks is odd but maybe there's lotsa potholes out there? door seal is weird, driver kept stepping on it and ripped it? O2 sensors should have lasted longer. valve cover gaskets gave out kinda quick too.
fwiw, mom's E39 530i gets 24mpg @ 80mph on a VERY hilly commute