i'd say that if you don't have proper tools and what not then 140 is a great price.

your basibly pullin your cam/gear to get to the seal there (meanint timing belt will be removed)

the crank seal is in the center of the oil pump so u'll be pulling the exhaust / dropping the oil pan / then pull in oil pump to do this correctly (obviously the crank pully bolt will have to be removed to do this, so be prepaired to have some breaking force).