Jason Snell wrote an interesting piece about Mac pricing and retina screens. He posits that the increased cost of retina Macs may be partly due to Apple creating an artificial divide between retina and non-retina Macs. This allows them to charge a premium price. There may be something to his hypothesis but I also think the additional costs of retina screens and the processors and graphics engines to drive them are a factor. (Jason concludes its probably a bit of both of these factors.) Apple is rarely the first to drop prices on hardware but I do think that eventually Apple will have retina Macs for under $1,000. Other vendors are already pulling this off.
Whether the reason for the increased cost of retina machines is actual costs or Apple padding its profit margin (or probably both), the next time you buy a Mac, I strongly suggest getting the reatina screen. Even if it requires saving your pennies a little bit longer, you'll love that retina screen every time you use your Mac.