Ride height is something that Ford really ****ed up on the Mustang. As far as looks are concerned, lowering the car is above all else. Now, $800 is EXTREMELY high to lower your car.
I bought my
Eibach Sportlines off a fellow member here for $100 and installed them myself. Grand total......$100. Even if I had not opted to do the install myself (which is really easy to do) the average quote I got was only $250.