Thanks a ton for your help guys. Unfortunately I ended up paying the $1800, as I'd already signed the work order and they'd already started working on my car. I think they did a good job, but with all the information I've been given I'm sure I could've gotten a better price.
I agree about the chain stores thing... they seem to replace everything that they can get away with and charge you for it, even if it doesn't need replacing. Since I'm in Minneapolis, I'm sure that there are some decent independent garages around.
Live and learn I guess. This $1800 is a hard lesson, but I won't forget it.