The model with the 21.5-inch screen will cost $1,299 and up, depending on the configuration. The model with a 27-inch screen will start at $1,799.
The iMac tacks the computer components to the back of a large LCD screen. The new models have no disk drive, helping make the edges one-fifth the thickness of the old model. They bulge considerably toward the middle of the back, however.
Apple revealed the new models a month ago.