Axle covers on Mercury Villager

After having her Villager in for a checkup, the mech. told my sister
that the axle covers were cracked and leaking fluid. A check on that
we found that its not fluid but grease in the covers. Also, there is no
evidence of grease on the floor. They gave an estimate of over a $1000
for the work. My nephew does this sort of work and said that that job
should cost no more than $225. This is a reputable dealer in Sterling
Hts. MI. Are they trying to do a number on Sis? Has anyone had
experience with this? Thanx in advance.

Norm