Review: New Apple iMac brings stunning 4K Retina screen to lower-cost model. Apple has added another Retina iMac to its lineup – this time a lower-cost model, at least by Apple pricing standards. Let’s get the bad news out of the way first. This is Apple so nothing is cheap. The new 21.5-inch iMac with Retina 4K display is $1,499. While that price is out of the reach of many consumers, it is $300 cheaper than the base 27-inch iMac with 5K Retina display, which starts at $1,799. That latter has been the only Retina iMac available to date.