In searching for alternatives, West Elm's Parachute Duvet Cover seems like an obvious choice. It's more than half the price of Anthropologie's Rosette Quilt and the color seems pretty close on-line (though I've been meaning to check it out in person).
Last, but not least, Target also offers a similar comforter worthy of consideration:
Although this comforter looks blue, the reviews state that its more of a grayish blue and the price definitely beats both Anthroplogie and West Elm.
So many choices... which one is your favorite?