So it is with Apple's MacBook Pro with Retina display. The 13in model arrived in October 2012 with a basic configuration of a 2.5GHz dual-core i5 processor, 8GB of memory and 128GB of flash storage for $1,899.

Four months later, the price was cut to $1,649 and a version with a 2.6GHz processor and 256GB of flash slotted in at $1,849.

Fast-forward to October 2013 and the entry-level MacBook Pro with Retina includes a 2.4GHz i5 but only 4GB of memory and the price has moved down to $1,599.

Higher specifications including i7 processors were available on a configure-to-order basis.

The latest change gives the base model a 2.6GHz dual-core i5 CPU, and the basic 13in MacBook Pro with Retina display again includes 8GB of RAM. It still costs $1599.

The other standard configurations are now 2.6GHz dual-core i5, 8GB of memory and 256GB of flash for $1,849, and a 2.8GHz dual-core i5 processor, 8GB of memory and 512GB of flash for $2,199.

They can be optioned up with Core i7 processors running at up to 3.0GHz, up to 16GB of memory and up to 1TB of flash.

Page 2: 15in MacBook Pro with Retina display also updated

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The 15in MacBook Pro with Retina display has been similarly tweaked.

The basic configuration has been upgraded to a 2.2GHz (previously 2.0GHz) quad-core i7 with 16GB (previously 8GB) of RAM and 256GB of flash. The price remains $2,499.

Or there's the 2.5GHz (previously 2.3GHz) i7 with 16GB of RAM and 512GB of flash for $2,999 (previously $A3,199).

The main options are processors running at up to 2.8GHz, and up to 1TB of flash.

"People love their MacBook Pro because of the thin and light, aluminium unibody design, beautiful Retina display, all day battery life and deep integration with OS X," said Apple senior vice president of worldwide marketing Philip Schiller.

"The MacBook Pro with Retina display gets even better with faster processors, more memory, more affordable configurations and a free upgrade to OS X Yosemite this spring."

If you're looking for something cheaper and don't feel the need for the high-resolution Retina display, there's still the 13in MacBook Pro with a conventional 1280x800 pixel screen.

$1,349 gets you a system with a 2.5GHz quad-core i5, 4GB of RAM and a 500GB hard drive, but that can be optioned up with a 2.9GHz CPU (+$180), 8GB of RAM (+$120), and either a 1TB hard drive (+$60) or a 128GB, 256Gb or 512GB SSD (+$180, +$420, +$780).