X2 - that car is worth some big $$$. Don't let the low riders see it
You can google auto repair estimates and get a few websites that will give you a good idea of price for your zip code. Try auto repair labor cost estimator in the search and you should get there. I find those estimates are close to reality, since they give you a price range and list parts and labor.
Just a tip on most repairs, look for someone who will let you get the parts, and buy OEM parts from online vendors to get the best parts. With a rear seal it is not such a big deal, but with mechanical/electrical parts it makes a big difference in price.