Apple has expanded its build-to-order options for the base model Retina display MacBook Pro. Originally, you had to get the US$2,199 model with a 2.3GHz Core i7 processor and 256GB of flash storage. Only the RAM could be upgraded from 8GB to 16GB (and this directly from Apple only).
Now you can — again, only through Apple — upgrade storage to 512GB of flash storage for $500 or 768GB of flash storage for $1000. Or you can replace the 2.3GHz CPU to 2.6GHz for $100.
Also, Apple is now allowing Mac buyers to have Pages, Numbers and/or Keynote pre-installed on their systems.