In addition to the other general comments here, I've scratched my head for quite a while about what they mean by a "drive shaft coupler".
The driveshaft in your car is COUPLED at both ends by a flex disc, sometimes called a guibo. It looks like this:
Those run about $150 at typical dealer prices.
There is also a universal joint in the middle of the two-piece driveshaft; however, it is not a separately-replaceable part that can be "ordered." (The driveshaft itself has to be replaced, a very expensive part, but it's more commonly rebuilt, though not by the dealer.)
So I think yes, if the dealership is trying to sell you one flex disc for $1,100 plus labor to install it, they are raking you over the coals.
Just thank them for their time, and head for a good indie shop. Have them inspect the driveline components (this will typically include the flex discs, universal joint, carrier and center bearing). If they recommend replacement, their quote will be hundreds less than the dealer, and it will include labor, too.
Oh, and I can't take my car to the dealer for anything without them performing a "complimentary" inspection, which usually results in a list of things that should be taken care of, none of which is less than $1,000.