If your mechanically inclined a lot of that you can do yourself in an afternoon the control arm bushings arent that hard. While the control arms are out might as well replace the ball joints. If there the factory ones its a lot easier to grind off the rivets on a bench than underneath the car. The oil pan gasket is another story i'm just assuming you have the 3800. Its a pain in the butt. I just pulled my whole motor and put in on a stand. I did a new upper intake, lower intake gasket oil pan gasket and timing cover gasket and seal. In about a weeks time. Just my two cents worth hope this helps save some money.
Don't want to be a total dick, but if you are looking to mod your car and didn't even check the fluids before bringing the car into a shop, you may be in over your head. And isn't $240 for a coolant flush insanely high?
As others have said, if you spend some time on here searching, there is a lot of good information.